diff --git a/conformance-test/libraryMethods.ts b/conformance-test/libraryMethods.ts
index eb09efb39a..73a325118b 100644
--- a/conformance-test/libraryMethods.ts
+++ b/conformance-test/libraryMethods.ts
@@ -42,7 +42,9 @@ export async function addLifecycleRuleInstancePrecondition(
   options: ConformanceTestOptions
 ) {
   await options.bucket!.addLifecycleRule({
-    action: 'delete',
+    action: {
+      type: 'Delete',
+    },
     condition: {
       age: 365 * 3, // Specified in days.
     },
@@ -53,7 +55,9 @@ export async function addLifecycleRule(options: ConformanceTestOptions) {
   if (options.preconditionRequired) {
     await options.bucket!.addLifecycleRule(
       {
-        action: 'delete',
+        action: {
+          type: 'Delete',
+        },
         condition: {
           age: 365 * 3, // Specified in days.
         },
@@ -64,7 +68,9 @@ export async function addLifecycleRule(options: ConformanceTestOptions) {
     );
   } else {
     await options.bucket!.addLifecycleRule({
-      action: 'delete',
+      action: {
+        type: 'Delete',
+      },
       condition: {
         age: 365 * 3, // Specified in days.
       },
@@ -104,7 +110,7 @@ export async function combine(options: ConformanceTestOptions) {
   await allFiles.save('allfiles contents');
   if (options.preconditionRequired) {
     await options.bucket!.combine(sources, allFiles, {
-      ifGenerationMatch: allFiles.metadata.generation,
+      ifGenerationMatch: allFiles.metadata.generation!,
     });
   } else {
     await options.bucket!.combine(sources, allFiles);
@@ -468,7 +474,9 @@ export async function copy(options: ConformanceTestOptions) {
 
   if (options.preconditionRequired) {
     await options.file!.copy('a-different-file.png', {
-      preconditionOpts: {ifGenerationMatch: newFile.metadata.generation},
+      preconditionOpts: {
+        ifGenerationMatch: newFile.metadata.generation!,
+      },
     });
   } else {
     await options.file!.copy('a-different-file.png');
diff --git a/src/acl.ts b/src/acl.ts
index e405b8f548..0e593f7569 100644
--- a/src/acl.ts
+++ b/src/acl.ts
@@ -12,7 +12,11 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-import {BodyResponseCallback, DecorateRequestOptions} from './nodejs-common';
+import {
+  BodyResponseCallback,
+  DecorateRequestOptions,
+  BaseMetadata,
+} from './nodejs-common';
 import {promisifyAll} from '@google-cloud/promisify';
 
 export interface AclOptions {
@@ -90,20 +94,18 @@ export interface AccessControlObject {
   projectTeam: string;
 }
 
-export interface AclMetadata {
+export interface AclMetadata extends BaseMetadata {
   bucket?: string;
   domain?: string;
   entity?: string;
   entityId?: string;
-  etag?: string;
-  id?: string;
-  kind?: string;
+  generation?: string;
+  object?: string;
   projectTeam?: {
     projectNumber?: string;
     team?: 'editors' | 'owners' | 'viewers';
   };
-  role?: 'OWNER' | 'READER' | 'WRITER';
-  selfLink?: string;
+  role?: 'OWNER' | 'READER' | 'WRITER' | 'FULL_CONTROL';
   [key: string]: unknown;
 }
 
diff --git a/src/bucket.ts b/src/bucket.ts
index 25227f9eae..2d29997965 100644
--- a/src/bucket.ts
+++ b/src/bucket.ts
@@ -19,13 +19,12 @@ import {
   DeleteCallback,
   ExistsCallback,
   GetConfig,
-  Metadata,
   MetadataCallback,
-  ResponseBody,
   ServiceObject,
   SetMetadataResponse,
   util,
 } from './nodejs-common';
+import {RequestResponse} from './nodejs-common/service-object';
 import {paginator} from '@google-cloud/paginator';
 import {promisifyAll} from '@google-cloud/promisify';
 import * as extend from 'extend';
@@ -38,16 +37,17 @@ import {promisify} from 'util';
 import retry = require('async-retry');
 import {convertObjKeysToSnakeCase} from './util';
 
-import {Acl} from './acl';
+import {Acl, AclMetadata} from './acl';
 import {Channel} from './channel';
 import {
   File,
   FileOptions,
   CreateResumableUploadOptions,
   CreateWriteStreamOptions,
+  FileMetadata,
 } from './file';
 import {Iam} from './iam';
-import {Notification} from './notification';
+import {Notification, NotificationMetadata} from './notification';
 import {
   Storage,
   Cors,
@@ -66,7 +66,7 @@ import {
 import {Readable} from 'stream';
 import {CRC32CValidatorGenerator} from './crc32c';
 import {URL} from 'url';
-import {SetMetadataOptions} from './nodejs-common/service-object';
+import {BaseMetadata, SetMetadataOptions} from './nodejs-common/service-object';
 
 interface SourceObject {
   name: string;
@@ -80,19 +80,19 @@ interface CreateNotificationQuery {
 interface MetadataOptions {
   predefinedAcl: string;
   userProject?: string;
-  ifGenerationMatch?: number;
-  ifGenerationNotMatch?: number;
-  ifMetagenerationMatch?: number;
-  ifMetagenerationNotMatch?: number;
+  ifGenerationMatch?: number | string;
+  ifGenerationNotMatch?: number | string;
+  ifMetagenerationMatch?: number | string;
+  ifMetagenerationNotMatch?: number | string;
 }
 
-export type GetFilesResponse = [File[], {}, Metadata];
+export type GetFilesResponse = [File[], {}, unknown];
 export interface GetFilesCallback {
   (
     err: Error | null,
     files?: File[],
     nextQuery?: {},
-    apiResponse?: Metadata
+    apiResponse?: unknown
   ): void;
 }
 
@@ -110,11 +110,28 @@ export interface AddLifecycleRuleOptions extends PreconditionOptions {
   append?: boolean;
 }
 
-export interface LifecycleRule {
-  action: {type: string; storageClass?: string} | string;
-  condition: {[key: string]: boolean | Date | number | string | string[]};
+export interface LifecycleAction {
+  type: 'Delete' | 'SetStorageClass' | 'AbortIncompleteMultipartUpload';
   storageClass?: string;
 }
+export interface LifecycleCondition {
+  age?: number;
+  createdBefore?: Date | string;
+  customTimeBefore?: Date | string;
+  daysSinceCustomTime?: number;
+  daysSinceNoncurrentTime?: number;
+  isLive?: boolean;
+  matchesPrefix?: string[];
+  matchesSuffix?: string[];
+  matchesStorageClass?: string[];
+  noncurrentTimeBefore?: Date | string;
+  numNewerVersions?: number;
+}
+
+export interface LifecycleRule {
+  action: LifecycleAction;
+  condition: LifecycleCondition;
+}
 
 export interface EnableLoggingOptions extends PreconditionOptions {
   bucket?: string | Bucket;
@@ -142,10 +159,10 @@ export interface CombineOptions extends PreconditionOptions {
 }
 
 export interface CombineCallback {
-  (err: Error | null, newFile: File | null, apiResponse: Metadata): void;
+  (err: Error | null, newFile: File | null, apiResponse: unknown): void;
 }
 
-export type CombineResponse = [File, Metadata];
+export type CombineResponse = [File, unknown];
 
 export interface CreateChannelConfig extends WatchAllOptions {
   address: string;
@@ -155,10 +172,10 @@ export interface CreateChannelOptions {
   userProject?: string;
 }
 
-export type CreateChannelResponse = [Channel, Metadata];
+export type CreateChannelResponse = [Channel, unknown];
 
 export interface CreateChannelCallback {
-  (err: Error | null, channel: Channel | null, apiResponse: Metadata): void;
+  (err: Error | null, channel: Channel | null, apiResponse: unknown): void;
 }
 
 export interface CreateNotificationOptions {
@@ -173,21 +190,21 @@ export interface CreateNotificationCallback {
   (
     err: Error | null,
     notification: Notification | null,
-    apiResponse: Metadata
+    apiResponse: unknown
   ): void;
 }
 
-export type CreateNotificationResponse = [Notification, Metadata];
+export type CreateNotificationResponse = [Notification, unknown];
 
 export interface DeleteBucketOptions {
   ignoreNotFound?: boolean;
   userProject?: string;
 }
 
-export type DeleteBucketResponse = [Metadata];
+export type DeleteBucketResponse = [unknown];
 
 export interface DeleteBucketCallback extends DeleteCallback {
-  (err: Error | null, apiResponse: Metadata): void;
+  (err: Error | null, apiResponse: unknown): void;
 }
 
 export interface DeleteFilesOptions
@@ -200,7 +217,7 @@ export interface DeleteFilesCallback {
   (err: Error | Error[] | null, apiResponse?: object): void;
 }
 
-export type DeleteLabelsResponse = [Metadata];
+export type DeleteLabelsResponse = [unknown];
 
 export type DeleteLabelsCallback = SetLabelsCallback;
 
@@ -208,16 +225,16 @@ export type DeleteLabelsOptions = PreconditionOptions;
 
 export type DisableRequesterPaysOptions = PreconditionOptions;
 
-export type DisableRequesterPaysResponse = [Metadata];
+export type DisableRequesterPaysResponse = [unknown];
 
 export interface DisableRequesterPaysCallback {
   (err?: Error | null, apiResponse?: object): void;
 }
 
-export type EnableRequesterPaysResponse = [Metadata];
+export type EnableRequesterPaysResponse = [unknown];
 
 export interface EnableRequesterPaysCallback {
-  (err?: Error | null, apiResponse?: Metadata): void;
+  (err?: Error | null, apiResponse?: unknown): void;
 }
 
 export type EnableRequesterPaysOptions = PreconditionOptions;
@@ -233,29 +250,91 @@ export interface GetBucketOptions extends GetConfig {
   userProject?: string;
 }
 
-export type GetBucketResponse = [Bucket, Metadata];
+export type GetBucketResponse = [Bucket, unknown];
 
 export interface GetBucketCallback {
-  (err: ApiError | null, bucket: Bucket | null, apiResponse: Metadata): void;
+  (err: ApiError | null, bucket: Bucket | null, apiResponse: unknown): void;
 }
 
 export interface GetLabelsOptions {
   userProject?: string;
 }
 
-export type GetLabelsResponse = [Metadata];
+export type GetLabelsResponse = [unknown];
 
 export interface GetLabelsCallback {
   (err: Error | null, labels: object | null): void;
 }
 
-export type GetBucketMetadataResponse = [Metadata, Metadata];
+export interface BucketMetadata extends BaseMetadata {
+  acl?: AclMetadata[];
+  autoclass?: {
+    enabled?: boolean;
+    toggleTime?: string;
+  };
+  billing?: {
+    requesterPays?: boolean;
+  };
+  cors?: Cors[];
+  customPlacementConfig?: {
+    dataLocations?: string[];
+  };
+  defaultEventBasedHold?: boolean;
+  defaultObjectAcl?: AclMetadata[];
+  encryption?: {
+    defaultKmsKeyName?: string;
+  } | null;
+  iamConfiguration?: {
+    publicAccessPrevention?: string;
+    uniformBucketLevelAccess?: {
+      enabled?: boolean;
+      lockedTime?: string;
+    };
+  };
+  labels?: {
+    [key: string]: string;
+  };
+  lifecycle?: {
+    rule?: LifecycleRule[];
+  } | null;
+  location?: string;
+  locationType?: string;
+  logging?: {
+    logBucket?: string;
+    logObjectPrefix?: string;
+  };
+  metageneration?: string;
+  name?: string;
+  owner?: {
+    entity?: string;
+    entityId?: string;
+  };
+  projectNumber?: string | number;
+  retentionPolicy?: {
+    effectiveTime?: string;
+    isLocked?: boolean;
+    retentionPeriod?: string | number;
+  } | null;
+  rpo?: string;
+  storageClass?: string;
+  timeCreated?: string;
+  updated?: string;
+  versioning?: {
+    enabled?: boolean;
+  };
+  website?: {
+    mainPageSuffix?: string;
+    notFoundPage?: string;
+  };
+}
+
+export type GetBucketMetadataResponse = [BucketMetadata, unknown];
 
 export interface GetBucketMetadataCallback {
   (
     err: ApiError | null,
-    metadata: Metadata | null,
-    apiResponse: Metadata
+    metadata: BucketMetadata | null,
+    apiResponse: unknown
   ): void;
 }
 
@@ -290,16 +369,16 @@ export interface GetNotificationsCallback {
   (
     err: Error | null,
     notifications: Notification[] | null,
-    apiResponse: Metadata
+    apiResponse: unknown
   ): void;
 }
 
-export type GetNotificationsResponse = [Notification[], Metadata];
+export type GetNotificationsResponse = [Notification[], unknown];
 
 export interface MakeBucketPrivateOptions {
   includeFiles?: boolean;
   force?: boolean;
-  metadata?: Metadata;
+  metadata?: BucketMetadata;
   userProject?: string;
   preconditionOpts?: PreconditionOptions;
 }
@@ -329,17 +408,17 @@ export interface SetBucketMetadataOptions extends PreconditionOptions {
   userProject?: string;
 }
 
-export type SetBucketMetadataResponse = [Metadata];
+export type SetBucketMetadataResponse = [BucketMetadata];
 
 export interface SetBucketMetadataCallback {
-  (err?: Error | null, metadata?: Metadata): void;
+  (err?: Error | null, metadata?: BucketMetadata): void;
 }
 
 export interface BucketLockCallback {
-  (err?: Error | null, apiResponse?: Metadata): void;
+  (err?: Error | null, apiResponse?: unknown): void;
 }
 
-export type BucketLockResponse = [Metadata];
+export type BucketLockResponse = [unknown];
 
 export interface Labels {
   [key: string]: string;
@@ -349,10 +428,10 @@ export interface SetLabelsOptions extends PreconditionOptions {
   userProject?: string;
 }
 
-export type SetLabelsResponse = [Metadata];
+export type SetLabelsResponse = [unknown];
 
 export interface SetLabelsCallback {
-  (err?: Error | null, metadata?: Metadata): void;
+  (err?: Error | null, metadata?: unknown): void;
 }
 
 export interface SetBucketStorageClassOptions extends PreconditionOptions {
@@ -363,10 +442,10 @@ export interface SetBucketStorageClassCallback {
   (err?: Error | null): void;
 }
 
-export type UploadResponse = [File, Metadata];
+export type UploadResponse = [File, unknown];
 
 export interface UploadCallback {
-  (err: Error | null, file?: File | null, apiResponse?: Metadata): void;
+  (err: Error | null, file?: File | null, apiResponse?: unknown): void;
 }
 
 export interface UploadOptions
@@ -681,8 +760,7 @@ export enum BucketExceptionMessages {
  * const bucket = storage.bucket('albums');
  * ```
  */
-class Bucket extends ServiceObject {
-  metadata: Metadata;
+class Bucket extends ServiceObject<Bucket, BucketMetadata> {
   name: string;
 
   /**
@@ -722,10 +800,10 @@ class Bucket extends ServiceObject {
 
     const requestQueryObject: {
       userProject?: string;
-      ifGenerationMatch?: number;
-      ifGenerationNotMatch?: number;
-      ifMetagenerationMatch?: number;
-      ifMetagenerationNotMatch?: number;
+      ifGenerationMatch?: number | string;
+      ifGenerationNotMatch?: number | string;
+      ifMetagenerationMatch?: number | string;
+      ifMetagenerationNotMatch?: number | string;
     } = {};
 
     if (options?.preconditionOpts?.ifGenerationMatch) {
@@ -1344,68 +1422,45 @@ class Bucket extends ServiceObject {
     options = options || {};
 
     const rules = Array.isArray(rule) ? rule : [rule];
-
-    const newLifecycleRules = rules.map(rule => {
-      if (typeof rule.action === 'object') {
-        // This is a raw-formatted rule object, the way the API expects.
-        // Just pass it through as-is.
-        return rule;
+    for (const curRule of rules) {
+      if (curRule.condition.createdBefore instanceof Date) {
+        curRule.condition.createdBefore = curRule.condition.createdBefore
+          .toISOString()
+          .replace(/T.+$/, '');
       }
-
-      const apiFormattedRule = {} as LifecycleRule;
-
-      apiFormattedRule.condition = {};
-      apiFormattedRule.action = {
-        type: rule.action.charAt(0).toUpperCase() + rule.action.slice(1),
-      };
-
-      if (rule.storageClass) {
-        apiFormattedRule.action.storageClass = rule.storageClass;
+      if (curRule.condition.customTimeBefore instanceof Date) {
+        curRule.condition.customTimeBefore = curRule.condition.customTimeBefore
+          .toISOString()
+          .replace(/T.+$/, '');
       }
-
-      for (const condition in rule.condition) {
-        if (rule.condition[condition] instanceof Date) {
-          apiFormattedRule.condition[condition] = (
-            rule.condition[condition] as Date
-          )
+      if (curRule.condition.noncurrentTimeBefore instanceof Date) {
+        curRule.condition.noncurrentTimeBefore =
+          curRule.condition.noncurrentTimeBefore
             .toISOString()
             .replace(/T.+$/, '');
-        } else {
-          apiFormattedRule.condition[condition] = rule.condition[condition];
-        }
       }
-
-      return apiFormattedRule;
-    });
+    }
 
     if (options.append === false) {
-      this.setMetadata(
-        {lifecycle: {rule: newLifecycleRules}},
-        options,
-        callback!
-      );
+      this.setMetadata({lifecycle: {rule: rules}}, options, callback!);
       return;
     }
 
     // The default behavior appends the previously-defined lifecycle rules with
     // the new ones just passed in by the user.
-    this.getMetadata((err: ApiError | null, metadata: Metadata) => {
+    this.getMetadata((err: ApiError | null, metadata: BucketMetadata) => {
       if (err) {
         callback!(err);
         return;
       }
 
-      const currentLifecycleRules = Array.isArray(
-        metadata.lifecycle && metadata.lifecycle.rule
-      )
-        ? metadata.lifecycle && metadata.lifecycle.rule
+      const currentLifecycleRules = Array.isArray(metadata.lifecycle?.rule)
+        ? metadata.lifecycle?.rule
         : [];
 
       this.setMetadata(
         {
-          lifecycle: {
-            rule: currentLifecycleRules.concat(newLifecycleRules),
-          },
+          lifecycle: {rule: currentLifecycleRules!.concat(rules)},
         },
         options as AddLifecycleRuleOptions,
         callback!
@@ -1579,7 +1634,9 @@ class Bucket extends ServiceObject {
             } as SourceObject;
 
             if (source.metadata && source.metadata.generation) {
-              sourceObject.generation = source.metadata.generation;
+              sourceObject.generation = parseInt(
+                source.metadata.generation.toString()
+              );
             }
 
             return sourceObject;
@@ -2342,9 +2399,12 @@ class Bucket extends ServiceObject {
       );
     }
 
-    const logBucket = config.bucket
-      ? (config.bucket as Bucket).id || config.bucket
-      : this.id;
+    let logBucket = this.id;
+    if (config.bucket && config.bucket instanceof Bucket) {
+      logBucket = config.bucket.id;
+    } else if (config.bucket && typeof config.bucket === 'string') {
+      logBucket = config.bucket;
+    }
 
     const options: PreconditionOptions = {};
     if (config?.ifMetagenerationMatch) {
@@ -2709,7 +2769,7 @@ class Bucket extends ServiceObject {
         }
 
         const itemsArray = resp.items ? resp.items : [];
-        const files = itemsArray.map((file: Metadata) => {
+        const files = itemsArray.map((file: FileMetadata) => {
           const options = {} as FileOptions;
 
           if (query.versions) {
@@ -2720,7 +2780,7 @@ class Bucket extends ServiceObject {
             options.kmsKeyName = file.kmsKeyName;
           }
 
-          const fileInstance = this.file(file.name, options);
+          const fileInstance = this.file(file.name!, options);
           fileInstance.metadata = file;
 
           return fileInstance;
@@ -2802,13 +2862,13 @@ class Bucket extends ServiceObject {
 
     this.getMetadata(
       options,
-      (err: ApiError | null, metadata: Metadata | null) => {
+      (err: ApiError | null, metadata: BucketMetadata | undefined) => {
         if (err) {
           callback!(err, null);
           return;
         }
 
-        callback!(null, metadata.labels || {});
+        callback!(null, metadata?.labels || {});
       }
     );
   }
@@ -2896,11 +2956,13 @@ class Bucket extends ServiceObject {
           return;
         }
         const itemsArray = resp.items ? resp.items : [];
-        const notifications = itemsArray.map((notification: Metadata) => {
-          const notificationInstance = this.notification(notification.id);
-          notificationInstance.metadata = notification;
-          return notificationInstance;
-        });
+        const notifications = itemsArray.map(
+          (notification: NotificationMetadata) => {
+            const notificationInstance = this.notification(notification.id!);
+            notificationInstance.metadata = notification;
+            return notificationInstance;
+          }
+        );
 
         callback!(null, notifications, resp);
       }
@@ -3272,7 +3334,7 @@ class Bucket extends ServiceObject {
     // so acl must explicitly be nullified.
     const metadata = extend({}, options.metadata, {acl: null});
 
-    this.setMetadata(metadata, query, err => {
+    this.setMetadata(metadata, query, (err: Error | null | undefined) => {
       if (err) {
         callback!(err);
       }
@@ -3496,7 +3558,7 @@ class Bucket extends ServiceObject {
     );
   }
 
-  request(reqOpts: DecorateRequestOptions): Promise<[ResponseBody, Metadata]>;
+  request(reqOpts: DecorateRequestOptions): Promise<RequestResponse>;
   request(
     reqOpts: DecorateRequestOptions,
     callback: BodyResponseCallback
@@ -3512,7 +3574,7 @@ class Bucket extends ServiceObject {
   request(
     reqOpts: DecorateRequestOptions,
     callback?: BodyResponseCallback
-  ): void | Promise<[ResponseBody, Metadata]> {
+  ): void | Promise<RequestResponse> {
     if (this.userProject && (!reqOpts.qs || !reqOpts.qs.userProject)) {
       reqOpts.qs = extend(reqOpts.qs, {userProject: this.userProject});
     }
@@ -3598,25 +3660,28 @@ class Bucket extends ServiceObject {
   }
 
   setMetadata(
-    metadata: Metadata,
+    metadata: BucketMetadata,
     options?: SetMetadataOptions
-  ): Promise<SetMetadataResponse>;
-  setMetadata(metadata: Metadata, callback: MetadataCallback): void;
+  ): Promise<SetMetadataResponse<BucketMetadata>>;
+  setMetadata(
+    metadata: BucketMetadata,
+    callback: MetadataCallback<BucketMetadata>
+  ): void;
   setMetadata(
-    metadata: Metadata,
+    metadata: BucketMetadata,
     options: SetMetadataOptions,
-    callback: MetadataCallback
+    callback: MetadataCallback<BucketMetadata>
   ): void;
   setMetadata(
-    metadata: Metadata,
-    optionsOrCallback: SetMetadataOptions | MetadataCallback,
-    cb?: MetadataCallback
-  ): Promise<SetMetadataResponse> | void {
+    metadata: BucketMetadata,
+    optionsOrCallback: SetMetadataOptions | MetadataCallback<BucketMetadata>,
+    cb?: MetadataCallback<BucketMetadata>
+  ): Promise<SetMetadataResponse<BucketMetadata>> | void {
     const options =
       typeof optionsOrCallback === 'object' ? optionsOrCallback : {};
     cb =
       typeof optionsOrCallback === 'function'
-        ? (optionsOrCallback as MetadataCallback)
+        ? (optionsOrCallback as MetadataCallback<BucketMetadata>)
         : cb;
 
     this.disableAutoRetryConditionallyIdempotent_(
@@ -3697,7 +3762,7 @@ class Bucket extends ServiceObject {
     this.setMetadata(
       {
         retentionPolicy: {
-          retentionPeriod: duration,
+          retentionPeriod: duration.toString(),
         },
       },
       options,
diff --git a/src/channel.ts b/src/channel.ts
index f0dff46ddc..ec4db1a35f 100644
--- a/src/channel.ts
+++ b/src/channel.ts
@@ -12,13 +12,13 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-import {Metadata, ServiceObject, util} from './nodejs-common';
+import {BaseMetadata, ServiceObject, util} from './nodejs-common';
 import {promisifyAll} from '@google-cloud/promisify';
 
 import {Storage} from './storage';
 
 export interface StopCallback {
-  (err: Error | null, apiResponse?: Metadata): void;
+  (err: Error | null, apiResponse?: unknown): void;
 }
 
 /**
@@ -38,7 +38,7 @@ export interface StopCallback {
  * const channel = storage.channel('id', 'resource-id');
  * ```
  */
-class Channel extends ServiceObject {
+class Channel extends ServiceObject<Channel, BaseMetadata> {
   constructor(storage: Storage, id: string, resourceId: string) {
     const config = {
       parent: storage,
@@ -60,7 +60,7 @@ class Channel extends ServiceObject {
     this.metadata.resourceId = resourceId;
   }
 
-  stop(): Promise<Metadata>;
+  stop(): Promise<unknown>;
   stop(callback: StopCallback): void;
   /**
    * @typedef {array} StopResponse
@@ -96,7 +96,7 @@ class Channel extends ServiceObject {
    * });
    * ```
    */
-  stop(callback?: StopCallback): Promise<Metadata> | void {
+  stop(callback?: StopCallback): Promise<unknown> | void {
     callback = callback || util.noop;
     this.request(
       {
diff --git a/src/file.ts b/src/file.ts
index 1237fd01d4..31b58b918c 100644
--- a/src/file.ts
+++ b/src/file.ts
@@ -17,7 +17,6 @@ import {
   DecorateRequestOptions,
   GetConfig,
   Interceptor,
-  Metadata,
   MetadataCallback,
   ServiceObject,
   SetMetadataResponse,
@@ -42,7 +41,7 @@ import {
   Storage,
 } from './storage';
 import {AvailableServiceObjectMethods, Bucket} from './bucket';
-import {Acl} from './acl';
+import {Acl, AclMetadata} from './acl';
 import {
   GetSignedUrlResponse,
   SigningError,
@@ -72,8 +71,10 @@ import {URL} from 'url';
 
 import retry = require('async-retry');
 import {
+  BaseMetadata,
   DeleteCallback,
   DeleteOptions,
+  RequestResponse,
   SetMetadataOptions,
 } from './nodejs-common/service-object';
 import * as r from 'teeny-request';
@@ -83,7 +84,7 @@ export interface GetExpirationDateCallback {
   (
     err: Error | null,
     expirationDate?: Date | null,
-    apiResponse?: Metadata
+    apiResponse?: unknown
   ): void;
 }
 
@@ -152,20 +153,20 @@ export interface GetFileMetadataOptions {
   userProject?: string;
 }
 
-export type GetFileMetadataResponse = [Metadata, Metadata];
+export type GetFileMetadataResponse = [FileMetadata, unknown];
 
 export interface GetFileMetadataCallback {
-  (err: Error | null, metadata?: Metadata, apiResponse?: Metadata): void;
+  (err: Error | null, metadata?: FileMetadata, apiResponse?: unknown): void;
 }
 
 export interface GetFileOptions extends GetConfig {
   userProject?: string;
 }
 
-export type GetFileResponse = [File, Metadata];
+export type GetFileResponse = [File, unknown];
 
 export interface GetFileCallback {
-  (err: Error | null, file?: File, apiResponse?: Metadata): void;
+  (err: Error | null, file?: File, apiResponse?: unknown): void;
 }
 
 export interface FileExistsOptions {
@@ -183,10 +184,10 @@ export interface DeleteFileOptions {
   userProject?: string;
 }
 
-export type DeleteFileResponse = [Metadata];
+export type DeleteFileResponse = [unknown];
 
 export interface DeleteFileCallback {
-  (err: Error | null, apiResponse?: Metadata): void;
+  (err: Error | null, apiResponse?: unknown): void;
 }
 
 export type PredefinedAcl =
@@ -200,7 +201,7 @@ export type PredefinedAcl =
 export interface CreateResumableUploadOptions {
   chunkSize?: number;
   highWaterMark?: number;
-  metadata?: Metadata;
+  metadata?: FileMetadata;
   origin?: string;
   offset?: number;
   predefinedAcl?: PredefinedAcl;
@@ -226,13 +227,13 @@ export interface CreateWriteStreamOptions extends CreateResumableUploadOptions {
 }
 
 export interface MakeFilePrivateOptions {
-  metadata?: Metadata;
+  metadata?: FileMetadata;
   strict?: boolean;
   userProject?: string;
   preconditionOpts?: PreconditionOptions;
 }
 
-export type MakeFilePrivateResponse = [Metadata];
+export type MakeFilePrivateResponse = [unknown];
 
 export type MakeFilePrivateCallback = SetFileMetadataCallback;
 
@@ -242,19 +243,19 @@ export interface IsPublicCallback {
 
 export type IsPublicResponse = [boolean];
 
-export type MakeFilePublicResponse = [Metadata];
+export type MakeFilePublicResponse = [unknown];
 
 export interface MakeFilePublicCallback {
-  (err?: Error | null, apiResponse?: Metadata): void;
+  (err?: Error | null, apiResponse?: unknown): void;
 }
 
-export type MoveResponse = [Metadata];
+export type MoveResponse = [unknown];
 
 export interface MoveCallback {
   (
     err: Error | null,
     destinationFile?: File | null,
-    apiResponse?: Metadata
+    apiResponse?: unknown
   ): void;
 }
 
@@ -311,17 +312,17 @@ export interface CopyOptions {
   contentType?: string;
   contentDisposition?: string;
   destinationKmsKeyName?: string;
-  metadata?: Metadata;
+  metadata?: FileMetadata;
   predefinedAcl?: string;
   token?: string;
   userProject?: string;
   preconditionOpts?: PreconditionOptions;
 }
 
-export type CopyResponse = [File, Metadata];
+export type CopyResponse = [File, unknown];
 
 export interface CopyCallback {
-  (err: Error | null, file?: File | null, apiResponse?: Metadata): void;
+  (err: Error | null, file?: File | null, apiResponse?: unknown): void;
 }
 
 export type DownloadResponse = [Buffer];
@@ -341,10 +342,10 @@ interface CopyQuery {
   userProject?: string;
   destinationKmsKeyName?: string;
   destinationPredefinedAcl?: string;
-  ifGenerationMatch?: number;
-  ifGenerationNotMatch?: number;
-  ifMetagenerationMatch?: number;
-  ifMetagenerationNotMatch?: number;
+  ifGenerationMatch?: number | string;
+  ifGenerationNotMatch?: number | string;
+  ifMetagenerationMatch?: number | string;
+  ifMetagenerationNotMatch?: number | string;
 }
 
 interface FileQuery {
@@ -375,12 +376,12 @@ export interface SetFileMetadataOptions {
 }
 
 export interface SetFileMetadataCallback {
-  (err?: Error | null, apiResponse?: Metadata): void;
+  (err?: Error | null, apiResponse?: unknown): void;
 }
 
-export type SetFileMetadataResponse = [Metadata];
+export type SetFileMetadataResponse = [unknown];
 
-export type SetStorageClassResponse = [Metadata];
+export type SetStorageClassResponse = [unknown];
 
 export interface SetStorageClassOptions {
   userProject?: string;
@@ -392,7 +393,46 @@ interface SetStorageClassRequest extends SetStorageClassOptions {
 }
 
 export interface SetStorageClassCallback {
-  (err?: Error | null, apiResponse?: Metadata): void;
+  (err?: Error | null, apiResponse?: unknown): void;
+}
+
+export interface FileMetadata extends BaseMetadata {
+  acl?: AclMetadata[];
+  bucket?: string;
+  cacheControl?: string;
+  componentCount?: number;
+  contentDisposition?: string;
+  contentEncoding?: string;
+  contentLanguage?: string;
+  contentType?: string;
+  crc32c?: string;
+  customerEncryption?: {
+    encryptionAlgorithm?: string;
+    keySha256?: string;
+  };
+  customTime?: string;
+  eventBasedHold?: boolean | null;
+  generation?: string | number;
+  kmsKeyName?: string;
+  md5Hash?: string;
+  mediaLink?: string;
+  metadata?: {
+    [key: string]: string;
+  };
+  metageneration?: string | number;
+  name?: string;
+  owner?: {
+    entity?: string;
+    entityId?: string;
+  };
+  retentionExpirationTime?: string;
+  size?: string | number;
+  storageClass?: string;
+  temporaryHold?: boolean | null;
+  timeCreated?: string;
+  timeDeleted?: string;
+  timeStorageClassUpdated?: string;
+  updated?: string;
 }
 
 export class RequestError extends Error {
@@ -427,7 +467,7 @@ export enum FileExceptionMessages {
  *
  * @class
  */
-class File extends ServiceObject<File> {
+class File extends ServiceObject<File, FileMetadata> {
   acl: Acl;
   crc32cGenerator: CRC32CValidatorGenerator;
   bucket: Bucket;
@@ -435,7 +475,6 @@ class File extends ServiceObject<File> {
   kmsKeyName?: string;
   userProject?: string;
   signer?: URLSigner;
-  metadata: Metadata;
   name: string;
 
   generation?: number;
@@ -1432,11 +1471,11 @@ class File extends ServiceObject<File> {
     const onResponse = (
       err: Error | null,
       _body: ResponseBody,
-      rawResponseStream: Metadata
+      rawResponseStream: unknown
     ) => {
       if (err) {
         // Get error message from the body.
-        this.getBufferFromReadable(rawResponseStream).then(body => {
+        this.getBufferFromReadable(rawResponseStream as Readable).then(body => {
           err.message = body.toString('utf8');
           throughStream.destroy(err);
         });
@@ -1444,7 +1483,7 @@ class File extends ServiceObject<File> {
         return;
       }
 
-      const headers = rawResponseStream.toJSON().headers;
+      const headers = (rawResponseStream as ResponseBody).toJSON().headers;
       const isCompressed = headers['content-encoding'] === 'gzip';
       const hashes: {crc32c?: string; md5?: string} = {};
 
@@ -1499,7 +1538,7 @@ class File extends ServiceObject<File> {
       }
 
       pipeline(
-        rawResponseStream,
+        rawResponseStream as Readable,
         ...(transformStreams as [Transform]),
         throughStream,
         onComplete
@@ -1851,27 +1890,27 @@ class File extends ServiceObject<File> {
     options = extend(true, {metadata: {}}, options);
 
     if (options.contentType) {
-      options.metadata.contentType = options.contentType;
+      options!.metadata!.contentType = options.contentType;
     }
 
     if (
-      !options.metadata.contentType ||
-      options.metadata.contentType === 'auto'
+      !options!.metadata!.contentType ||
+      options!.metadata!.contentType === 'auto'
     ) {
       const detectedContentType = mime.getType(this.name);
       if (detectedContentType) {
-        options.metadata.contentType = detectedContentType;
+        options!.metadata!.contentType = detectedContentType;
       }
     }
 
     let gzip = options.gzip;
 
     if (gzip === 'auto') {
-      gzip = compressible(options.metadata.contentType);
+      gzip = compressible(options!.metadata!.contentType || '');
     }
 
     if (gzip) {
-      options.metadata.contentEncoding = 'gzip';
+      options!.metadata!.contentEncoding = 'gzip';
     }
 
     let crc32c = true;
@@ -2232,7 +2271,7 @@ class File extends ServiceObject<File> {
     callback?: GetExpirationDateCallback
   ): void | Promise<GetExpirationDateResponse> {
     this.getMetadata(
-      (err: ApiError | null, metadata: Metadata, apiResponse: Metadata) => {
+      (err: ApiError | null, metadata: FileMetadata, apiResponse: unknown) => {
         if (err) {
           callback!(err, null, apiResponse);
           return;
@@ -3439,7 +3478,7 @@ class File extends ServiceObject<File> {
     this.move(destinationFile, options, callback);
   }
 
-  request(reqOpts: DecorateRequestOptions): Promise<[ResponseBody, Metadata]>;
+  request(reqOpts: DecorateRequestOptions): Promise<RequestResponse>;
   request(
     reqOpts: DecorateRequestOptions,
     callback: BodyResponseCallback
@@ -3455,7 +3494,7 @@ class File extends ServiceObject<File> {
   request(
     reqOpts: DecorateRequestOptions,
     callback?: BodyResponseCallback
-  ): void | Promise<[ResponseBody, Metadata]> {
+  ): void | Promise<RequestResponse> {
     return this.parent.request.call(this, reqOpts, callback!);
   }
 
@@ -3653,25 +3692,28 @@ class File extends ServiceObject<File> {
   }
 
   setMetadata(
-    metadata: Metadata,
+    metadata: FileMetadata,
     options?: SetMetadataOptions
-  ): Promise<SetMetadataResponse>;
-  setMetadata(metadata: Metadata, callback: MetadataCallback): void;
+  ): Promise<SetMetadataResponse<FileMetadata>>;
+  setMetadata(
+    metadata: FileMetadata,
+    callback: MetadataCallback<FileMetadata>
+  ): void;
   setMetadata(
-    metadata: Metadata,
+    metadata: FileMetadata,
     options: SetMetadataOptions,
-    callback: MetadataCallback
+    callback: MetadataCallback<FileMetadata>
   ): void;
   setMetadata(
-    metadata: Metadata,
-    optionsOrCallback: SetMetadataOptions | MetadataCallback,
-    cb?: MetadataCallback
-  ): Promise<SetMetadataResponse> | void {
+    metadata: FileMetadata,
+    optionsOrCallback: SetMetadataOptions | MetadataCallback<FileMetadata>,
+    cb?: MetadataCallback<FileMetadata>
+  ): Promise<SetMetadataResponse<FileMetadata>> | void {
     const options =
       typeof optionsOrCallback === 'object' ? optionsOrCallback : {};
     cb =
       typeof optionsOrCallback === 'function'
-        ? (optionsOrCallback as MetadataCallback)
+        ? (optionsOrCallback as MetadataCallback<FileMetadata>)
         : cb;
 
     this.disableAutoRetryConditionallyIdempotent_(
diff --git a/src/hmacKey.ts b/src/hmacKey.ts
index 33f11431a9..4621fef5e2 100644
--- a/src/hmacKey.ts
+++ b/src/hmacKey.ts
@@ -13,13 +13,12 @@
 // limitations under the License.
 
 import {
-  Metadata,
   ServiceObject,
   Methods,
   MetadataCallback,
   SetMetadataResponse,
 } from './nodejs-common';
-import {SetMetadataOptions} from './nodejs-common/service-object';
+import {BaseMetadata, SetMetadataOptions} from './nodejs-common/service-object';
 import {IdempotencyStrategy, Storage} from './storage';
 import {promisifyAll} from '@google-cloud/promisify';
 
@@ -27,10 +26,9 @@ export interface HmacKeyOptions {
   projectId?: string;
 }
 
-export interface HmacKeyMetadata {
-  accessId: string;
+export interface HmacKeyMetadata extends BaseMetadata {
+  accessId?: string;
   etag?: string;
-  id?: string;
   projectId?: string;
   serviceAccountEmail?: string;
   state?: string;
@@ -51,10 +49,10 @@ export interface SetHmacKeyMetadata {
 }
 
 export interface HmacKeyMetadataCallback {
-  (err: Error | null, metadata?: HmacKeyMetadata, apiResponse?: Metadata): void;
+  (err: Error | null, metadata?: HmacKeyMetadata, apiResponse?: unknown): void;
 }
 
-export type HmacKeyMetadataResponse = [HmacKeyMetadata, Metadata];
+export type HmacKeyMetadataResponse = [HmacKeyMetadata, unknown];
 
 /**
  * The API-formatted resource description of the HMAC key.
@@ -74,8 +72,7 @@ export type HmacKeyMetadataResponse = [HmacKeyMetadata, Metadata];
  *
  * @class
  */
-export class HmacKey extends ServiceObject<HmacKeyMetadata | undefined> {
-  metadata: HmacKeyMetadata | undefined;
+export class HmacKey extends ServiceObject<HmacKey, HmacKeyMetadata> {
   /**
    * A reference to the {@link Storage} associated with this {@link HmacKey}
    * instance.
@@ -370,20 +367,23 @@ export class HmacKey extends ServiceObject<HmacKeyMetadata | undefined> {
    * @param {object} callback.apiResponse - The full API response.
    */
   setMetadata(
-    metadata: Metadata,
+    metadata: HmacKeyMetadata,
     options?: SetMetadataOptions
-  ): Promise<SetMetadataResponse>;
-  setMetadata(metadata: Metadata, callback: MetadataCallback): void;
+  ): Promise<SetMetadataResponse<HmacKeyMetadata>>;
   setMetadata(
-    metadata: Metadata,
+    metadata: HmacKeyMetadata,
+    callback: MetadataCallback<HmacKeyMetadata>
+  ): void;
+  setMetadata(
+    metadata: HmacKeyMetadata,
     options: SetMetadataOptions,
-    callback: MetadataCallback
+    callback: MetadataCallback<HmacKeyMetadata>
   ): void;
   setMetadata(
-    metadata: Metadata,
-    optionsOrCallback: SetMetadataOptions | MetadataCallback,
-    cb?: MetadataCallback
-  ): Promise<SetMetadataResponse> | void {
+    metadata: HmacKeyMetadata,
+    optionsOrCallback: SetMetadataOptions | MetadataCallback<HmacKeyMetadata>,
+    cb?: MetadataCallback<HmacKeyMetadata>
+  ): Promise<SetMetadataResponse<HmacKeyMetadata>> | void {
     // ETag preconditions are not currently supported. Retries should be disabled if the idempotency strategy is not set to RetryAlways
     if (
       this.storage.retryOptions.idempotencyStrategy !==
@@ -395,7 +395,7 @@ export class HmacKey extends ServiceObject<HmacKeyMetadata | undefined> {
       typeof optionsOrCallback === 'object' ? optionsOrCallback : {};
     cb =
       typeof optionsOrCallback === 'function'
-        ? (optionsOrCallback as MetadataCallback)
+        ? (optionsOrCallback as MetadataCallback<HmacKeyMetadata>)
         : cb;
 
     super
diff --git a/src/iam.ts b/src/iam.ts
index 1f27622d75..fc65aeac05 100644
--- a/src/iam.ts
+++ b/src/iam.ts
@@ -12,11 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-import {
-  BodyResponseCallback,
-  DecorateRequestOptions,
-  Metadata,
-} from './nodejs-common';
+import {BodyResponseCallback, DecorateRequestOptions} from './nodejs-common';
 import {promisifyAll} from '@google-cloud/promisify';
 
 import {Bucket} from './bucket';
@@ -27,7 +23,7 @@ export interface GetPolicyOptions {
   requestedPolicyVersion?: number;
 }
 
-export type GetPolicyResponse = [Policy, Metadata];
+export type GetPolicyResponse = [Policy, unknown];
 
 /**
  * @callback GetPolicyCallback
@@ -36,7 +32,7 @@ export type GetPolicyResponse = [Policy, Metadata];
  * @param {object} apiResponse The full API response.
  */
 export interface GetPolicyCallback {
-  (err?: Error | null, acl?: Policy, apiResponse?: Metadata): void;
+  (err?: Error | null, acl?: Policy, apiResponse?: unknown): void;
 }
 
 /**
@@ -53,7 +49,7 @@ export interface SetPolicyOptions {
  * @property {object} 0 The policy.
  * @property {object} 1 The full API response.
  */
-export type SetPolicyResponse = [Policy, Metadata];
+export type SetPolicyResponse = [Policy, unknown];
 
 /**
  * @callback SetPolicyCallback
@@ -88,7 +84,7 @@ export interface Expr {
  * @property {object} 0 A subset of permissions that the caller is allowed.
  * @property {object} 1 The full API response.
  */
-export type TestIamPermissionsResponse = [{[key: string]: boolean}, Metadata];
+export type TestIamPermissionsResponse = [{[key: string]: boolean}, unknown];
 
 /**
  * @callback TestIamPermissionsCallback
@@ -100,7 +96,7 @@ export interface TestIamPermissionsCallback {
   (
     err?: Error | null,
     acl?: {[key: string]: boolean} | null,
-    apiResponse?: Metadata
+    apiResponse?: unknown
   ): void;
 }
 
diff --git a/src/nodejs-common/index.ts b/src/nodejs-common/index.ts
index f90c514baa..293105b950 100644
--- a/src/nodejs-common/index.ts
+++ b/src/nodejs-common/index.ts
@@ -23,12 +23,12 @@ export {
 } from './service';
 
 export {
+  BaseMetadata,
   DeleteCallback,
   ExistsCallback,
   GetConfig,
   InstanceResponseCallback,
   Interceptor,
-  Metadata,
   MetadataCallback,
   MetadataResponse,
   Methods,
diff --git a/src/nodejs-common/service-object.ts b/src/nodejs-common/service-object.ts
index afc5491c8c..78ef276da2 100644
--- a/src/nodejs-common/service-object.ts
+++ b/src/nodejs-common/service-object.ts
@@ -27,7 +27,7 @@ import {
   util,
 } from './util';
 
-export type RequestResponse = [Metadata, r.Response];
+export type RequestResponse = [unknown, r.Response];
 
 export interface ServiceObjectParent {
   interceptors: Interceptor[];
@@ -45,12 +45,10 @@ export interface Interceptor {
 
 export type GetMetadataOptions = object;
 
-// eslint-disable-next-line @typescript-eslint/no-explicit-any
-export type Metadata = any;
-export type MetadataResponse = [Metadata, r.Response];
-export type MetadataCallback = (
+export type MetadataResponse<K> = [K, r.Response];
+export type MetadataCallback<K> = (
   err: Error | null,
-  metadata?: Metadata,
+  metadata?: K,
   apiResponse?: r.Response
 ) => void;
 
@@ -114,10 +112,10 @@ export interface CreateCallback<T> {
 
 export type DeleteOptions = {
   ignoreNotFound?: boolean;
-  ifGenerationMatch?: number;
-  ifGenerationNotMatch?: number;
-  ifMetagenerationMatch?: number;
-  ifMetagenerationNotMatch?: number;
+  ifGenerationMatch?: number | string;
+  ifGenerationNotMatch?: number | string;
+  ifMetagenerationMatch?: number | string;
+  ifMetagenerationNotMatch?: number | string;
 } & object;
 export interface DeleteCallback {
   (err: Error | null, apiResponse?: r.Response): void;
@@ -129,16 +127,24 @@ export interface GetConfig {
    */
   autoCreate?: boolean;
 }
-type GetOrCreateOptions = GetConfig & CreateOptions;
+export type GetOrCreateOptions = GetConfig & CreateOptions;
 export type GetResponse<T> = [T, r.Response];
 
 export interface ResponseCallback {
   (err?: Error | null, apiResponse?: r.Response): void;
 }
 
-export type SetMetadataResponse = [Metadata];
+export type SetMetadataResponse<K> = [K];
 export type SetMetadataOptions = object;
 
+export interface BaseMetadata {
+  id?: string;
+  kind?: string;
+  etag?: string;
+  selfLink?: string;
+  [key: string]: unknown;
+}
+
 /**
  * ServiceObject is a base class, meant to be inherited from by a "service
  * object," like a BigQuery dataset or Storage bucket.
@@ -151,8 +157,8 @@ export type SetMetadataOptions = object;
  * object requires specific behavior.
  */
 // eslint-disable-next-line @typescript-eslint/no-explicit-any
-class ServiceObject<T = any> extends EventEmitter {
-  metadata: Metadata;
+class ServiceObject<T, K extends BaseMetadata> extends EventEmitter {
+  metadata: K;
   baseUrl?: string;
   parent: ServiceObjectParent;
   id?: string;
@@ -181,7 +187,7 @@ class ServiceObject<T = any> extends EventEmitter {
    */
   constructor(config: ServiceObjectConfig) {
     super();
-    this.metadata = {};
+    this.metadata = {} as K;
     this.baseUrl = config.baseUrl;
     this.parent = config.parent; // Parent class.
     this.id = config.id; // Name or ID (e.g. dataset ID, bucket name, etc).
@@ -249,7 +255,7 @@ class ServiceObject<T = any> extends EventEmitter {
     // Wrap the callback to return *this* instance of the object, not the
     // newly-created one.
     // tslint: disable-next-line no-any
-    function onCreate(...args: [Error, ServiceObject<T>]) {
+    function onCreate(...args: [Error, ServiceObject<T, K>]) {
       const [err, instance] = args;
       if (!err) {
         self.metadata = instance.metadata;
@@ -409,10 +415,10 @@ class ServiceObject<T = any> extends EventEmitter {
           self.create(...args);
           return;
         }
-        callback!(err, null, metadata as r.Response);
+        callback!(err, null, metadata as unknown as r.Response);
         return;
       }
-      callback!(null, self as {} as T, metadata as r.Response);
+      callback!(null, self as {} as T, metadata as unknown as r.Response);
     });
   }
 
@@ -424,16 +430,16 @@ class ServiceObject<T = any> extends EventEmitter {
    * @param {object} callback.metadata - The metadata for this object.
    * @param {object} callback.apiResponse - The full API response.
    */
-  getMetadata(options?: GetMetadataOptions): Promise<MetadataResponse>;
-  getMetadata(options: GetMetadataOptions, callback: MetadataCallback): void;
-  getMetadata(callback: MetadataCallback): void;
+  getMetadata(options?: GetMetadataOptions): Promise<MetadataResponse<K>>;
+  getMetadata(options: GetMetadataOptions, callback: MetadataCallback<K>): void;
+  getMetadata(callback: MetadataCallback<K>): void;
   getMetadata(
-    optionsOrCallback: GetMetadataOptions | MetadataCallback,
-    cb?: MetadataCallback
-  ): Promise<MetadataResponse> | void {
+    optionsOrCallback: GetMetadataOptions | MetadataCallback<K>,
+    cb?: MetadataCallback<K>
+  ): Promise<MetadataResponse<K>> | void {
     const [options, callback] = util.maybeOptionsOrCallback<
       GetMetadataOptions,
-      MetadataCallback
+      MetadataCallback<K>
     >(optionsOrCallback, cb);
 
     const methodConfig =
@@ -484,23 +490,23 @@ class ServiceObject<T = any> extends EventEmitter {
    * @param {object} callback.apiResponse - The full API response.
    */
   setMetadata(
-    metadata: Metadata,
+    metadata: K,
     options?: SetMetadataOptions
-  ): Promise<SetMetadataResponse>;
-  setMetadata(metadata: Metadata, callback: MetadataCallback): void;
+  ): Promise<SetMetadataResponse<K>>;
+  setMetadata(metadata: K, callback: MetadataCallback<K>): void;
   setMetadata(
-    metadata: Metadata,
+    metadata: K,
     options: SetMetadataOptions,
-    callback: MetadataCallback
+    callback: MetadataCallback<K>
   ): void;
   setMetadata(
-    metadata: Metadata,
-    optionsOrCallback: SetMetadataOptions | MetadataCallback,
-    cb?: MetadataCallback
-  ): Promise<SetMetadataResponse> | void {
+    metadata: K,
+    optionsOrCallback: SetMetadataOptions | MetadataCallback<K>,
+    cb?: MetadataCallback<K>
+  ): Promise<SetMetadataResponse<K>> | void {
     const [options, callback] = util.maybeOptionsOrCallback<
       SetMetadataOptions,
-      MetadataCallback
+      MetadataCallback<K>
     >(optionsOrCallback, cb);
     const methodConfig =
       (typeof this.methods.setMetadata === 'object' &&
@@ -582,7 +588,6 @@ class ServiceObject<T = any> extends EventEmitter {
     if (reqOpts.shouldReturnStream) {
       return this.parent.requestStream(reqOpts);
     }
-
     this.parent.request(reqOpts, callback!);
   }
 
diff --git a/src/notification.ts b/src/notification.ts
index aff9d315c8..c24bf0c397 100644
--- a/src/notification.ts
+++ b/src/notification.ts
@@ -12,13 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-import {
-  ApiError,
-  Metadata,
-  MetadataCallback,
-  ServiceObject,
-  util,
-} from './nodejs-common';
+import {BaseMetadata, ServiceObject} from './nodejs-common';
 import {ResponseBody} from './nodejs-common/util';
 import {promisifyAll} from '@google-cloud/promisify';
 
@@ -37,7 +31,7 @@ export interface GetNotificationMetadataOptions {
  * @property {object} 0 The notification metadata.
  * @property {object} 1 The full API response.
  */
-export type GetNotificationMetadataResponse = [ResponseBody, Metadata];
+export type GetNotificationMetadataResponse = [ResponseBody, unknown];
 
 /**
  * @callback GetNotificationMetadataCallback
@@ -46,7 +40,7 @@ export type GetNotificationMetadataResponse = [ResponseBody, Metadata];
  * @param {object} apiResponse The full API response.
  */
 export interface GetNotificationMetadataCallback {
-  (err: Error | null, metadata?: ResponseBody, apiResponse?: Metadata): void;
+  (err: Error | null, metadata?: ResponseBody, apiResponse?: unknown): void;
 }
 
 /**
@@ -54,7 +48,7 @@ export interface GetNotificationMetadataCallback {
  * @property {Notification} 0 The {@link Notification}
  * @property {object} 1 The full API response.
  */
-export type GetNotificationResponse = [Notification, Metadata];
+export type GetNotificationResponse = [Notification, unknown];
 
 export interface GetNotificationOptions {
   /**
@@ -78,7 +72,7 @@ export interface GetNotificationCallback {
   (
     err: Error | null,
     notification?: Notification | null,
-    apiResponse?: Metadata
+    apiResponse?: unknown
   ): void;
 }
 
@@ -88,7 +82,17 @@ export interface GetNotificationCallback {
  * @param {object} apiResponse The full API response.
  */
 export interface DeleteNotificationCallback {
-  (err: Error | null, apiResponse?: Metadata): void;
+  (err: Error | null, apiResponse?: unknown): void;
+}
+
+export interface NotificationMetadata extends BaseMetadata {
+  custom_attributes?: {
+    [key: string]: string;
+  };
+  event_types?: string[];
+  object_name_prefix?: string;
+  payload_format?: 'JSON_API_V1' | 'NONE';
+  topic?: string;
 }
 
 /**
@@ -122,8 +126,15 @@ export interface DeleteNotificationCallback {
  * const notification = myBucket.notification('1');
  * ```
  */
-class Notification extends ServiceObject {
+class Notification extends ServiceObject<Notification, NotificationMetadata> {
   constructor(bucket: Bucket, id: string) {
+    const requestQueryObject: {
+      ifGenerationMatch?: number;
+      ifGenerationNotMatch?: number;
+      ifMetagenerationMatch?: number;
+      ifMetagenerationNotMatch?: number;
+    } = {};
+
     const methods = {
       /**
        * Creates a notification subscription for the bucket.
@@ -169,6 +180,127 @@ class Notification extends ServiceObject {
        */
       create: true,
 
+      /**
+       * @typedef {array} DeleteNotificationResponse
+       * @property {object} 0 The full API response.
+       */
+      /**
+       * Permanently deletes a notification subscription.
+       *
+       * See {@link https://cloud.google.com/storage/docs/json_api/v1/notifications/delete| Notifications: delete API Documentation}
+       *
+       * @param {object} [options] Configuration options.
+       * @param {string} [options.userProject] The ID of the project which will be
+       *     billed for the request.
+       * @param {DeleteNotificationCallback} [callback] Callback function.
+       * @returns {Promise<DeleteNotificationResponse>}
+       *
+       * @example
+       * ```
+       * const {Storage} = require('@google-cloud/storage');
+       * const storage = new Storage();
+       * const myBucket = storage.bucket('my-bucket');
+       * const notification = myBucket.notification('1');
+       *
+       * notification.delete(function(err, apiResponse) {});
+       *
+       * //-
+       * // If the callback is omitted, we'll return a Promise.
+       * //-
+       * notification.delete().then(function(data) {
+       *   const apiResponse = data[0];
+       * });
+       *
+       * ```
+       * @example <caption>include:samples/deleteNotification.js</caption>
+       * region_tag:storage_delete_bucket_notification
+       * Another example:
+       */
+      delete: {
+        reqOpts: {
+          qs: requestQueryObject,
+        },
+      },
+
+      /**
+       * Get a notification and its metadata if it exists.
+       *
+       * See {@link https://cloud.google.com/storage/docs/json_api/v1/notifications/get| Notifications: get API Documentation}
+       *
+       * @param {object} [options] Configuration options.
+       *     See {@link Bucket#createNotification} for create options.
+       * @param {boolean} [options.autoCreate] Automatically create the object if
+       *     it does not exist. Default: `false`.
+       * @param {string} [options.userProject] The ID of the project which will be
+       *     billed for the request.
+       * @param {GetNotificationCallback} [callback] Callback function.
+       * @return {Promise<GetNotificationCallback>}
+       *
+       * @example
+       * ```
+       * const {Storage} = require('@google-cloud/storage');
+       * const storage = new Storage();
+       * const myBucket = storage.bucket('my-bucket');
+       * const notification = myBucket.notification('1');
+       *
+       * notification.get(function(err, notification, apiResponse) {
+       *   // `notification.metadata` has been populated.
+       * });
+       *
+       * //-
+       * // If the callback is omitted, we'll return a Promise.
+       * //-
+       * notification.get().then(function(data) {
+       *   const notification = data[0];
+       *   const apiResponse = data[1];
+       * });
+       * ```
+       */
+      get: {
+        reqOpts: {
+          qs: requestQueryObject,
+        },
+      },
+
+      /**
+       * Get the notification's metadata.
+       *
+       * See {@link https://cloud.google.com/storage/docs/json_api/v1/notifications/get| Notifications: get API Documentation}
+       *
+       * @param {object} [options] Configuration options.
+       * @param {string} [options.userProject] The ID of the project which will be
+       *     billed for the request.
+       * @param {GetNotificationMetadataCallback} [callback] Callback function.
+       * @returns {Promise<GetNotificationMetadataResponse>}
+       *
+       * @example
+       * ```
+       * const {Storage} = require('@google-cloud/storage');
+       * const storage = new Storage();
+       * const myBucket = storage.bucket('my-bucket');
+       * const notification = myBucket.notification('1');
+       *
+       * notification.getMetadata(function(err, metadata, apiResponse) {});
+       *
+       * //-
+       * // If the callback is omitted, we'll return a Promise.
+       * //-
+       * notification.getMetadata().then(function(data) {
+       *   const metadata = data[0];
+       *   const apiResponse = data[1];
+       * });
+       *
+       * ```
+       * @example <caption>include:samples/getMetadataNotifications.js</caption>
+       * region_tag:storage_print_pubsub_bucket_notification
+       * Another example:
+       */
+      getMetadata: {
+        reqOpts: {
+          qs: requestQueryObject,
+        },
+      },
+
       /**
        * @typedef {array} NotificationExistsResponse
        * @property {boolean} 0 Whether the notification exists or not.
@@ -213,222 +345,6 @@ class Notification extends ServiceObject {
       methods,
     });
   }
-
-  delete(options?: DeleteNotificationOptions): Promise<[Metadata]>;
-  delete(
-    options: DeleteNotificationOptions,
-    callback: DeleteNotificationCallback
-  ): void;
-  delete(callback: DeleteNotificationCallback): void;
-  /**
-   * @typedef {array} DeleteNotificationResponse
-   * @property {object} 0 The full API response.
-   */
-  /**
-   * Permanently deletes a notification subscription.
-   *
-   * See {@link https://cloud.google.com/storage/docs/json_api/v1/notifications/delete| Notifications: delete API Documentation}
-   *
-   * @param {object} [options] Configuration options.
-   * @param {string} [options.userProject] The ID of the project which will be
-   *     billed for the request.
-   * @param {DeleteNotificationCallback} [callback] Callback function.
-   * @returns {Promise<DeleteNotificationResponse>}
-   *
-   * @example
-   * ```
-   * const {Storage} = require('@google-cloud/storage');
-   * const storage = new Storage();
-   * const myBucket = storage.bucket('my-bucket');
-   * const notification = myBucket.notification('1');
-   *
-   * notification.delete(function(err, apiResponse) {});
-   *
-   * //-
-   * // If the callback is omitted, we'll return a Promise.
-   * //-
-   * notification.delete().then(function(data) {
-   *   const apiResponse = data[0];
-   * });
-   *
-   * ```
-   * @example <caption>include:samples/deleteNotification.js</caption>
-   * region_tag:storage_delete_bucket_notification
-   * Another example:
-   */
-  delete(
-    optionsOrCallback?: DeleteNotificationOptions | DeleteNotificationCallback,
-    callback?: DeleteNotificationCallback
-  ): void | Promise<[Metadata]> {
-    const options =
-      typeof optionsOrCallback === 'object' ? optionsOrCallback : {};
-    callback =
-      typeof optionsOrCallback === 'function' ? optionsOrCallback : callback;
-    this.request(
-      {
-        method: 'DELETE',
-        uri: '',
-        qs: options,
-      },
-      callback || util.noop
-    );
-  }
-
-  get(options?: GetNotificationOptions): Promise<GetNotificationResponse>;
-  get(options: GetNotificationOptions, callback: GetNotificationCallback): void;
-  get(callback: GetNotificationCallback): void;
-  /**
-   * Get a notification and its metadata if it exists.
-   *
-   * See {@link https://cloud.google.com/storage/docs/json_api/v1/notifications/get| Notifications: get API Documentation}
-   *
-   * @param {object} [options] Configuration options.
-   *     See {@link Bucket#createNotification} for create options.
-   * @param {boolean} [options.autoCreate] Automatically create the object if
-   *     it does not exist. Default: `false`.
-   * @param {string} [options.userProject] The ID of the project which will be
-   *     billed for the request.
-   * @param {GetNotificationCallback} [callback] Callback function.
-   * @return {Promise<GetNotificationCallback>}
-   *
-   * @example
-   * ```
-   * const {Storage} = require('@google-cloud/storage');
-   * const storage = new Storage();
-   * const myBucket = storage.bucket('my-bucket');
-   * const notification = myBucket.notification('1');
-   *
-   * notification.get(function(err, notification, apiResponse) {
-   *   // `notification.metadata` has been populated.
-   * });
-   *
-   * //-
-   * // If the callback is omitted, we'll return a Promise.
-   * //-
-   * notification.get().then(function(data) {
-   *   const notification = data[0];
-   *   const apiResponse = data[1];
-   * });
-   * ```
-   */
-  get(
-    optionsOrCallback?: GetNotificationOptions | GetNotificationCallback,
-    callback?: GetNotificationCallback
-  ): void | Promise<GetNotificationResponse> {
-    const options =
-      typeof optionsOrCallback === 'object' ? optionsOrCallback : {};
-    callback =
-      typeof optionsOrCallback === 'function' ? optionsOrCallback : callback;
-
-    const autoCreate = options.autoCreate;
-    delete options.autoCreate;
-
-    const onCreate = (
-      err: ApiError | null,
-      notification: Notification,
-      apiResponse: Metadata
-    ) => {
-      if (err) {
-        if (err.code === 409) {
-          this.get(options, callback!);
-          return;
-        }
-
-        callback!(err, null, apiResponse);
-        return;
-      }
-
-      callback!(null, notification, apiResponse);
-    };
-
-    this.getMetadata(options, (err, metadata) => {
-      if (err) {
-        if ((err as ApiError).code === 404 && autoCreate) {
-          const args = [] as object[];
-
-          if (Object.keys(options).length > 0) {
-            args.push(options);
-          }
-
-          args.push(onCreate);
-
-          // eslint-disable-next-line
-          this.create.apply(this, args as any);
-          return;
-        }
-
-        callback!(err, null, metadata);
-        return;
-      }
-
-      callback!(null, this, metadata);
-    });
-  }
-
-  getMetadata(
-    options?: GetNotificationMetadataOptions
-  ): Promise<GetNotificationMetadataResponse>;
-  getMetadata(
-    options: GetNotificationMetadataOptions,
-    callback: MetadataCallback
-  ): void;
-  getMetadata(callback: MetadataCallback): void;
-  /**
-   * Get the notification's metadata.
-   *
-   * See {@link https://cloud.google.com/storage/docs/json_api/v1/notifications/get| Notifications: get API Documentation}
-   *
-   * @param {object} [options] Configuration options.
-   * @param {string} [options.userProject] The ID of the project which will be
-   *     billed for the request.
-   * @param {GetNotificationMetadataCallback} [callback] Callback function.
-   * @returns {Promise<GetNotificationMetadataResponse>}
-   *
-   * @example
-   * ```
-   * const {Storage} = require('@google-cloud/storage');
-   * const storage = new Storage();
-   * const myBucket = storage.bucket('my-bucket');
-   * const notification = myBucket.notification('1');
-   *
-   * notification.getMetadata(function(err, metadata, apiResponse) {});
-   *
-   * //-
-   * // If the callback is omitted, we'll return a Promise.
-   * //-
-   * notification.getMetadata().then(function(data) {
-   *   const metadata = data[0];
-   *   const apiResponse = data[1];
-   * });
-   *
-   * ```
-   * @example <caption>include:samples/getMetadataNotifications.js</caption>
-   * region_tag:storage_print_pubsub_bucket_notification
-   * Another example:
-   */
-  getMetadata(
-    optionsOrCallback?: GetNotificationMetadataOptions | MetadataCallback,
-    callback?: MetadataCallback
-  ): void | Promise<GetNotificationMetadataResponse> {
-    const options =
-      typeof optionsOrCallback === 'object' ? optionsOrCallback : {};
-    callback =
-      typeof optionsOrCallback === 'function' ? optionsOrCallback : callback;
-    this.request(
-      {
-        uri: '',
-        qs: options,
-      },
-      (err, resp) => {
-        if (err) {
-          callback!(err, null, resp);
-          return;
-        }
-        this.metadata = resp;
-        callback!(null, this.metadata, resp);
-      }
-    );
-  }
 }
 
 /*! Developer Documentation
diff --git a/src/storage.ts b/src/storage.ts
index ba77ee164c..8aa8e6b744 100644
--- a/src/storage.ts
+++ b/src/storage.ts
@@ -12,12 +12,12 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-import {ApiError, Metadata, Service, ServiceOptions} from './nodejs-common';
+import {ApiError, Service, ServiceOptions} from './nodejs-common';
 import {paginator} from '@google-cloud/paginator';
 import {promisifyAll} from '@google-cloud/promisify';
 import {Readable} from 'stream';
 
-import {Bucket} from './bucket';
+import {Bucket, BucketMetadata} from './bucket';
 import {Channel} from './channel';
 import {File} from './file';
 import {normalize} from './util';
@@ -33,12 +33,12 @@ export interface GetServiceAccountOptions {
 export interface ServiceAccount {
   emailAddress?: string;
 }
-export type GetServiceAccountResponse = [ServiceAccount, Metadata];
+export type GetServiceAccountResponse = [ServiceAccount, unknown];
 export interface GetServiceAccountCallback {
   (
     err: Error | null,
     serviceAccount?: ServiceAccount,
-    apiResponse?: Metadata
+    apiResponse?: unknown
   ): void;
 }
 
@@ -64,10 +64,10 @@ export interface RetryOptions {
 }
 
 export interface PreconditionOptions {
-  ifGenerationMatch?: number;
-  ifGenerationNotMatch?: number;
-  ifMetagenerationMatch?: number;
-  ifMetagenerationNotMatch?: number;
+  ifGenerationMatch?: number | string;
+  ifGenerationNotMatch?: number | string;
+  ifMetagenerationMatch?: number | string;
+  ifMetagenerationNotMatch?: number | string;
 }
 
 export interface StorageOptions extends ServiceOptions {
@@ -130,19 +130,19 @@ export interface CreateBucketRequest {
   versioning?: Versioning;
 }
 
-export type CreateBucketResponse = [Bucket, Metadata];
+export type CreateBucketResponse = [Bucket, unknown];
 
 export interface BucketCallback {
-  (err: Error | null, bucket?: Bucket | null, apiResponse?: Metadata): void;
+  (err: Error | null, bucket?: Bucket | null, apiResponse?: unknown): void;
 }
 
-export type GetBucketsResponse = [Bucket[], {}, Metadata];
+export type GetBucketsResponse = [Bucket[], {}, unknown];
 export interface GetBucketsCallback {
   (
     err: Error | null,
     buckets: Bucket[],
     nextQuery?: {},
-    apiResponse?: Metadata
+    apiResponse?: unknown
   ): void;
 }
 export interface GetBucketsRequest {
@@ -192,7 +192,7 @@ export interface GetHmacKeysCallback {
     err: Error | null,
     hmacKeys: HmacKey[] | null,
     nextQuery?: {},
-    apiResponse?: Metadata
+    apiResponse?: unknown
   ): void;
 }
 
@@ -1156,7 +1156,7 @@ export class Storage extends Service {
         }
 
         const metadata = resp.metadata;
-        const hmacKey = this.hmacKey(metadata.accessId, {
+        const hmacKey = this.hmacKey(metadata.accessId!, {
           projectId: metadata.projectId,
         });
         hmacKey.metadata = resp.metadata;
@@ -1276,8 +1276,8 @@ export class Storage extends Service {
         }
 
         const itemsArray = resp.items ? resp.items : [];
-        const buckets = itemsArray.map((bucket: Metadata) => {
-          const bucketInstance = this.bucket(bucket.id);
+        const buckets = itemsArray.map((bucket: BucketMetadata) => {
+          const bucketInstance = this.bucket(bucket.id!);
           bucketInstance.metadata = bucket;
           return bucketInstance;
         });
@@ -1399,7 +1399,7 @@ export class Storage extends Service {
 
         const itemsArray = resp.items ? resp.items : [];
         const hmacKeys = itemsArray.map((hmacKey: HmacKeyMetadata) => {
-          const hmacKeyInstance = this.hmacKey(hmacKey.accessId, {
+          const hmacKeyInstance = this.hmacKey(hmacKey.accessId!, {
             projectId: hmacKey.projectId,
           });
           hmacKeyInstance.metadata = hmacKey;
diff --git a/src/transfer-manager.ts b/src/transfer-manager.ts
index 58cd75c110..ec6d252f4a 100644
--- a/src/transfer-manager.ts
+++ b/src/transfer-manager.ts
@@ -322,7 +322,7 @@ export class TransferManager {
         : fileOrName;
 
     const fileInfo = await file.get();
-    const size = parseInt(fileInfo[0].metadata.size);
+    const size = parseInt(fileInfo[0].metadata.size!.toString());
     // If the file size does not meet the threshold download it as a single chunk.
     if (size < DOWNLOAD_IN_CHUNKS_FILE_SIZE_THRESHOLD) {
       limit = pLimit(1);
diff --git a/system-test/storage.ts b/system-test/storage.ts
index 4517272cc2..adfabe7ed8 100644
--- a/system-test/storage.ts
+++ b/system-test/storage.ts
@@ -425,10 +425,9 @@ describe('storage', () => {
           resumable: false,
         });
         const [metadata] = await file.getMetadata();
-        assert.strictEqual(
-          metadata.customerEncryption.encryptionAlgorithm,
-          'AES256'
-        );
+        const encyrptionAlgorithm =
+          metadata.customerEncryption?.encryptionAlgorithm;
+        assert.strictEqual(encyrptionAlgorithm, 'AES256');
       });
 
       it('should set custom encryption in a resumable upload', async () => {
@@ -438,10 +437,9 @@ describe('storage', () => {
           resumable: true,
         });
         const [metadata] = await file.getMetadata();
-        assert.strictEqual(
-          metadata.customerEncryption.encryptionAlgorithm,
-          'AES256'
-        );
+        const encyrptionAlgorithm =
+          metadata.customerEncryption?.encryptionAlgorithm;
+        assert.strictEqual(encyrptionAlgorithm, 'AES256');
       });
 
       it('should make a file public during the upload', async () => {
@@ -630,7 +628,7 @@ describe('storage', () => {
       );
       const [bucketMetadata] = await bucket.getMetadata();
       const publicAccessPreventionStatus =
-        bucketMetadata.iamConfiguration.publicAccessPrevention;
+        bucketMetadata!.iamConfiguration!.publicAccessPrevention;
       return assert.strictEqual(
         publicAccessPreventionStatus,
         PUBLIC_ACCESS_PREVENTION_ENFORCED
@@ -679,7 +677,7 @@ describe('storage', () => {
       );
       const [bucketMetadata] = await bucket.getMetadata();
       const publicAccessPreventionStatus =
-        bucketMetadata.iamConfiguration.publicAccessPrevention;
+        bucketMetadata!.iamConfiguration!.publicAccessPrevention;
       return assert.strictEqual(
         publicAccessPreventionStatus,
         PUBLIC_ACCESS_PREVENTION_INHERITED
@@ -704,7 +702,7 @@ describe('storage', () => {
     it('UBLA modification on PAP bucket does not affect pap setting', async () => {
       const [bucketMetadata] = await bucket.getMetadata();
       const publicAccessPreventionStatus =
-        bucketMetadata.iamConfiguration.publicAccessPrevention;
+        bucketMetadata!.iamConfiguration!.publicAccessPrevention;
       await bucket.setMetadata({
         iamConfiguration: {
           uniformBucketLevelAccess: {
@@ -714,7 +712,7 @@ describe('storage', () => {
       });
       const [updatedBucketMetadata] = await bucket.getMetadata();
       return assert.strictEqual(
-        updatedBucketMetadata.iamConfiguration.publicAccessPrevention,
+        updatedBucketMetadata!.iamConfiguration!.publicAccessPrevention,
         publicAccessPreventionStatus
       );
     });
@@ -729,14 +727,15 @@ describe('storage', () => {
       });
       const [bucketMetadata] = await bucket.getMetadata();
       const ublaSetting =
-        bucketMetadata.iamConfiguration.uniformBucketLevelAccess.enabled;
+        bucketMetadata!.iamConfiguration!.uniformBucketLevelAccess!.enabled;
       await setPublicAccessPrevention(
         bucket,
         PUBLIC_ACCESS_PREVENTION_INHERITED
       );
       const [updatedBucketMetadata] = await bucket.getMetadata();
       return assert.strictEqual(
-        updatedBucketMetadata.iamConfiguration.uniformBucketLevelAccess.enabled,
+        updatedBucketMetadata!.iamConfiguration!.uniformBucketLevelAccess!
+          .enabled,
         ublaSetting
       );
     });
@@ -1061,33 +1060,33 @@ describe('storage', () => {
         },
       });
       let [metadata] = await bucket.getMetadata();
-      const timestampEnabled = metadata.autoclass.toggleTime;
-      assert.strictEqual(metadata.autoclass.enabled, true);
+      const timestampEnabled = metadata!.autoclass!.toggleTime;
+      assert.strictEqual(metadata!.autoclass!.enabled, true);
       [metadata] = await bucket.setMetadata({
         autoclass: {
           enabled: false,
         },
       });
-      const timestampDisabled = metadata.autoclass.toggleTime;
-      assert.strictEqual(metadata.autoclass.enabled, false);
-      assert.strictEqual(timestampDisabled > timestampEnabled, true);
+      const timestampDisabled = metadata!.autoclass!.toggleTime;
+      assert.strictEqual(metadata!.autoclass!.enabled, false);
+      assert.strictEqual(timestampDisabled! > timestampEnabled!, true);
     });
 
     describe('locationType', () => {
       const types = ['multi-region', 'region', 'dual-region'];
 
       beforeEach(() => {
-        delete bucket.metadata;
+        bucket.metadata = {};
       });
 
       it('should be available from getting a bucket', async () => {
         const [metadata] = await bucket.getMetadata();
-        assert(types.includes(metadata.locationType));
+        assert(types.includes(metadata.locationType!));
       });
 
       it('should be available from creating a bucket', async () => {
         const [bucket] = await storage.createBucket(generateName());
-        assert(types.includes(bucket.metadata.locationType));
+        assert(types.includes(bucket.metadata.locationType!));
         return bucket.delete();
       });
 
@@ -1097,19 +1096,19 @@ describe('storage', () => {
         assert(buckets.length > 0);
 
         buckets.forEach(bucket => {
-          assert(types.includes(bucket.metadata.locationType));
+          assert(types.includes(bucket.metadata.locationType!));
         });
       });
 
       it('should be available from setting retention policy', async () => {
         await bucket.setRetentionPeriod(RETENTION_DURATION_SECONDS);
-        assert(types.includes(bucket.metadata.locationType));
+        assert(types.includes(bucket.metadata.locationType!));
         await bucket.removeRetentionPeriod();
       });
 
       it('should be available from updating a bucket', async () => {
         await bucket.setLabels({a: 'b'});
-        assert(types.includes(bucket.metadata.locationType));
+        assert(types.includes(bucket.metadata.locationType!));
       });
     });
 
@@ -1165,14 +1164,16 @@ describe('storage', () => {
   describe('bucket object lifecycle management', () => {
     it('should add a rule', async () => {
       await bucket.addLifecycleRule({
-        action: 'delete',
+        action: {
+          type: 'Delete',
+        },
         condition: {
           age: 30,
           isLive: true,
         },
       });
-      const rules = [].slice.call(bucket.metadata.lifecycle.rule);
 
+      const rules = [].slice.call(bucket.metadata.lifecycle?.rule);
       assert.deepStrictEqual(rules.pop(), {
         action: {
           type: 'Delete',
@@ -1186,40 +1187,46 @@ describe('storage', () => {
 
     it('should append a new rule', async () => {
       const numExistingRules =
-        (bucket.metadata.lifecycle && bucket.metadata.lifecycle.rule.length) ||
+        (bucket.metadata.lifecycle && bucket.metadata.lifecycle.rule!.length) ||
         0;
 
       await bucket.addLifecycleRule({
-        action: 'delete',
+        action: {
+          type: 'Delete',
+        },
         condition: {
           age: 30,
           isLive: true,
         },
       });
       await bucket.addLifecycleRule({
-        action: 'setStorageClass',
+        action: {
+          type: 'SetStorageClass',
+          storageClass: 'coldline',
+        },
         condition: {
           age: 60,
           isLive: true,
         },
-        storageClass: 'coldline',
       });
       assert.strictEqual(
-        bucket.metadata.lifecycle.rule.length,
+        bucket.metadata.lifecycle!.rule!.length,
         numExistingRules + 2
       );
     });
 
     it('should add a prefix rule', async () => {
       await bucket.addLifecycleRule({
-        action: 'delete',
+        action: {
+          type: 'Delete',
+        },
         condition: {
           matchesPrefix: [TESTS_PREFIX],
         },
       });
 
       assert(
-        bucket.metadata.lifecycle.rule.some(
+        bucket.metadata.lifecycle!.rule!.some(
           (rule: LifecycleRule) =>
             typeof rule.action === 'object' &&
             rule.action.type === 'Delete' &&
@@ -1232,14 +1239,16 @@ describe('storage', () => {
 
     it('should add a suffix rule', async () => {
       await bucket.addLifecycleRule({
-        action: 'delete',
+        action: {
+          type: 'Delete',
+        },
         condition: {
           matchesSuffix: [TESTS_PREFIX, 'test_suffix'],
         },
       });
 
       assert(
-        bucket.metadata.lifecycle.rule.some(
+        bucket.metadata.lifecycle!.rule!.some(
           (rule: LifecycleRule) =>
             typeof rule.action === 'object' &&
             rule.action.type === 'Delete' &&
@@ -1250,12 +1259,14 @@ describe('storage', () => {
 
     it('should convert a rule with createdBefore to a date in string', async () => {
       await bucket.addLifecycleRule({
-        action: 'delete',
+        action: {
+          type: 'Delete',
+        },
         condition: {
           createdBefore: new Date('2018'),
         },
       });
-      const rules = [].slice.call(bucket.metadata.lifecycle.rule);
+      const rules = [].slice.call(bucket.metadata.lifecycle?.rule);
       assert.deepStrictEqual(rules.pop(), {
         action: {
           type: 'Delete',
@@ -1270,7 +1281,9 @@ describe('storage', () => {
       const NONCURRENT_TIME_BEFORE = '2020-01-01';
 
       await bucket.addLifecycleRule({
-        action: 'delete',
+        action: {
+          type: 'Delete',
+        },
         condition: {
           noncurrentTimeBefore: new Date(NONCURRENT_TIME_BEFORE),
           daysSinceNoncurrentTime: 100,
@@ -1278,7 +1291,7 @@ describe('storage', () => {
       });
 
       assert(
-        bucket.metadata.lifecycle.rule.some(
+        bucket.metadata.lifecycle!.rule!.some(
           (rule: LifecycleRule) =>
             typeof rule.action === 'object' &&
             rule.action.type === 'Delete' &&
@@ -1292,7 +1305,9 @@ describe('storage', () => {
       const CUSTOM_TIME_BEFORE = '2020-01-01';
 
       await bucket.addLifecycleRule({
-        action: 'delete',
+        action: {
+          type: 'Delete',
+        },
         condition: {
           customTimeBefore: new Date(CUSTOM_TIME_BEFORE),
           daysSinceCustomTime: 100,
@@ -1300,7 +1315,7 @@ describe('storage', () => {
       });
 
       assert(
-        bucket.metadata.lifecycle.rule.some(
+        bucket.metadata.lifecycle!.rule!.some(
           (rule: LifecycleRule) =>
             typeof rule.action === 'object' &&
             rule.action.type === 'Delete' &&
@@ -1375,7 +1390,7 @@ describe('storage', () => {
           },
         });
         await bucket.getMetadata();
-        assert.strictEqual(bucket.metadata.versioning.enabled, true);
+        assert.strictEqual(bucket.metadata!.versioning!.enabled, true);
       });
 
       it('should by default create a bucket without versioning set', async () => {
@@ -1398,7 +1413,7 @@ describe('storage', () => {
         });
         await bucket.getMetadata();
         assert.strictEqual(
-          bucket.metadata.retentionPolicy.retentionPeriod,
+          bucket.metadata!.retentionPolicy!.retentionPeriod,
           `${RETENTION_DURATION_SECONDS}`
         );
       });
@@ -1409,7 +1424,7 @@ describe('storage', () => {
         await bucket.setRetentionPeriod(RETENTION_DURATION_SECONDS);
         await bucket.getMetadata();
         assert.strictEqual(
-          bucket.metadata.retentionPolicy.retentionPeriod,
+          bucket.metadata!.retentionPolicy!.retentionPeriod,
           `${RETENTION_DURATION_SECONDS}`
         );
       });
@@ -1420,7 +1435,7 @@ describe('storage', () => {
         await bucket.setRetentionPeriod(RETENTION_DURATION_SECONDS);
         await bucket.getMetadata();
 
-        await bucket.lock(bucket.metadata.metageneration);
+        await bucket.lock(bucket.metadata!.metageneration!.toString());
         await assert.rejects(
           bucket.setRetentionPeriod(RETENTION_DURATION_SECONDS / 2),
           (err: ApiError) => {
@@ -1435,7 +1450,7 @@ describe('storage', () => {
         await bucket.setRetentionPeriod(RETENTION_DURATION_SECONDS);
         await bucket.getMetadata();
         assert.strictEqual(
-          bucket.metadata.retentionPolicy.retentionPeriod,
+          bucket.metadata!.retentionPolicy!.retentionPeriod,
           `${RETENTION_DURATION_SECONDS}`
         );
 
@@ -1585,7 +1600,7 @@ describe('storage', () => {
 
     it('should have enabled requesterPays functionality', async () => {
       const [metadata] = await bucket.getMetadata();
-      assert.strictEqual(metadata.billing.requesterPays, true);
+      assert.strictEqual(metadata.billing!.requesterPays, true);
     });
 
     // These tests will verify that the requesterPays functionality works from
@@ -2098,7 +2113,7 @@ describe('storage', () => {
       bucket.upload(FILES.big.path, (err: Error | null, file?: File | null) => {
         assert.ifError(err);
 
-        const fileSize = file!.metadata.size;
+        const fileSize = parseInt(file!.metadata.size!.toString());
         const byteRange = {
           start: Math.floor((fileSize * 1) / 3),
           end: Math.floor((fileSize * 2) / 3),
@@ -2493,7 +2508,7 @@ describe('storage', () => {
           // Strip the project ID, as it could be the placeholder locally, but
           // the real value upstream.
           const projectIdRegExp = /^.+\/locations/;
-          const actualKmsKeyName = metadata.kmsKeyName.replace(
+          const actualKmsKeyName = metadata!.kmsKeyName!.replace(
             projectIdRegExp,
             ''
           );
@@ -2513,7 +2528,7 @@ describe('storage', () => {
           // Strip the project ID, as it could be the placeholder locally,
           // but the real value upstream.
           const projectIdRegExp = /^.+\/locations/;
-          const actualKmsKeyName = metadata.kmsKeyName.replace(
+          const actualKmsKeyName = metadata!.kmsKeyName!.replace(
             projectIdRegExp,
             ''
           );
@@ -2573,7 +2588,10 @@ describe('storage', () => {
           // the real value upstream.
           const projectIdRegExp = /^.+\/locations/;
           const actualKmsKeyName =
-            metadata.encryption.defaultKmsKeyName.replace(projectIdRegExp, '');
+            metadata!.encryption!.defaultKmsKeyName!.replace(
+              projectIdRegExp,
+              ''
+            );
           const expectedKmsKeyName = kmsKeyName.replace(projectIdRegExp, '');
           assert.strictEqual(actualKmsKeyName, expectedKmsKeyName);
         });
@@ -2598,7 +2616,7 @@ describe('storage', () => {
 
           assert.strictEqual(
             fileMetadata.kmsKeyName,
-            `${metadata.encryption.defaultKmsKeyName}/cryptoKeyVersions/1`
+            `${metadata!.encryption!.defaultKmsKeyName}/cryptoKeyVersions/1`
           );
         });
       });
@@ -2625,10 +2643,10 @@ describe('storage', () => {
       const [copiedFile] = await file.copy('CloudLogoCopy', copyOpts);
       const [metadata] = await copiedFile.getMetadata();
       assert.strictEqual(
-        typeof metadata.metadata.originalProperty,
+        typeof metadata!.metadata!.originalProperty,
         'undefined'
       );
-      assert.strictEqual(metadata.metadata.newProperty, 'true');
+      assert.strictEqual(metadata!.metadata!.newProperty, 'true');
       await Promise.all([file.delete, copiedFile.delete()]);
     });
 
@@ -3627,7 +3645,7 @@ describe('storage', () => {
         const [metadata] = await file.getMetadata();
 
         assert.equal(metadata.crc32c, expected);
-        assert(crc32c.validate(metadata.crc32c));
+        assert(crc32c.validate(metadata.crc32c!));
       }
     });
   });
diff --git a/test/acl.ts b/test/acl.ts
index 9339b6377a..bee7fe2e48 100644
--- a/test/acl.ts
+++ b/test/acl.ts
@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-import {DecorateRequestOptions, Metadata, util} from '../src/nodejs-common';
+import {DecorateRequestOptions, util} from '../src/nodejs-common';
 import * as assert from 'assert';
 import {describe, it, before, beforeEach} from 'mocha';
 import * as proxyquire from 'proxyquire';
@@ -147,7 +147,7 @@ describe('storage/acl', () => {
 
       acl.add(
         {entity: ENTITY, role: ROLE},
-        (err: Error, acls: {}, apiResponse: Metadata) => {
+        (err: Error, acls: {}, apiResponse: unknown) => {
           assert.deepStrictEqual(resp, apiResponse);
           done();
         }
@@ -214,7 +214,7 @@ describe('storage/acl', () => {
         callback(null, resp);
       };
 
-      acl.delete({entity: ENTITY}, (err: Error, apiResponse: Metadata) => {
+      acl.delete({entity: ENTITY}, (err: Error, apiResponse: unknown) => {
         assert.deepStrictEqual(resp, apiResponse);
         done();
       });
@@ -351,7 +351,7 @@ describe('storage/acl', () => {
         callback(null, resp);
       };
 
-      acl.get((err: Error, acls: Array<{}>, apiResponse: Metadata) => {
+      acl.get((err: Error, acls: Array<{}>, apiResponse: unknown) => {
         assert.deepStrictEqual(resp, apiResponse);
         done();
       });
@@ -441,7 +441,7 @@ describe('storage/acl', () => {
       const config = {entity: ENTITY, role: ROLE};
       acl.update(
         config,
-        (err: Error, acls: Array<{}>, apiResponse: Metadata) => {
+        (err: Error, acls: Array<{}>, apiResponse: unknown) => {
           assert.deepStrictEqual(resp, apiResponse);
           done();
         }
diff --git a/test/bucket.ts b/test/bucket.ts
index 3951a1c525..d48cef3b83 100644
--- a/test/bucket.ts
+++ b/test/bucket.ts
@@ -13,8 +13,8 @@
 // limitations under the License.
 
 import {
+  BaseMetadata,
   DecorateRequestOptions,
-  Metadata,
   ServiceObject,
   ServiceObjectConfig,
   util,
@@ -35,6 +35,7 @@ import {
   File,
   SetFileMetadataOptions,
   FileOptions,
+  FileMetadata,
 } from '../src/file';
 import {PromisifyAllOptions} from '@google-cloud/promisify';
 import {
@@ -45,6 +46,8 @@ import {
   GetBucketSignedUrlConfig,
   AvailableServiceObjectMethods,
   BucketExceptionMessages,
+  BucketMetadata,
+  LifecycleRule,
 } from '../src/bucket';
 import {AddAclOptions} from '../src/acl';
 import {Policy} from '../src/iam';
@@ -58,7 +61,7 @@ class FakeFile {
   bucket: Bucket;
   name: string;
   options: FileOptions;
-  metadata: {};
+  metadata: FileMetadata;
   createWriteStream: Function;
   delete: Function;
   isSameFile = () => false;
@@ -71,7 +74,7 @@ class FakeFile {
     this.metadata = {};
 
     this.createWriteStream = (options: CreateWriteStreamOptions) => {
-      this.metadata = options.metadata;
+      this.metadata = options.metadata!;
       const ws = new stream.Writable();
       ws.write = () => {
         ws.emit('complete');
@@ -160,7 +163,7 @@ class FakeIam {
   }
 }
 
-class FakeServiceObject extends ServiceObject {
+class FakeServiceObject extends ServiceObject<FakeServiceObject, BaseMetadata> {
   calledWith_: IArguments;
   constructor(config: ServiceObjectConfig) {
     super(config);
@@ -470,54 +473,8 @@ describe('Bucket', () => {
         condition: {},
       };
 
-      bucket.setMetadata = (metadata: Metadata) => {
-        assert.deepStrictEqual(metadata.lifecycle.rule, [rule]);
-        done();
-      };
-
-      bucket.addLifecycleRule(rule, assert.ifError);
-    });
-
-    it('should properly capitalize rule action', done => {
-      const rule = {
-        action: 'delete',
-        condition: {},
-      };
-
-      bucket.setMetadata = (metadata: Metadata) => {
-        assert.deepStrictEqual(metadata.lifecycle.rule, [
-          {
-            action: {
-              type: rule.action.charAt(0).toUpperCase() + rule.action.slice(1),
-            },
-            condition: rule.condition,
-          },
-        ]);
-
-        done();
-      };
-
-      bucket.addLifecycleRule(rule, assert.ifError);
-    });
-
-    it('should properly set the storage class', done => {
-      const rule = {
-        action: 'setStorageClass',
-        storageClass: 'storage class',
-        condition: {},
-      };
-
-      bucket.setMetadata = (metadata: Metadata) => {
-        assert.deepStrictEqual(metadata.lifecycle.rule, [
-          {
-            action: {
-              type: rule.action.charAt(0).toUpperCase() + rule.action.slice(1),
-              storageClass: rule.storageClass,
-            },
-            condition: rule.condition,
-          },
-        ]);
-
+      bucket.setMetadata = (metadata: BucketMetadata) => {
+        assert.deepStrictEqual(metadata.lifecycle!.rule, [rule]);
         done();
       };
 
@@ -526,17 +483,19 @@ describe('Bucket', () => {
 
     it('should properly set condition', done => {
       const rule = {
-        action: 'delete',
+        action: {
+          type: 'Delete',
+        },
         condition: {
           age: 30,
         },
       };
 
-      bucket.setMetadata = (metadata: Metadata) => {
-        assert.deepStrictEqual(metadata.lifecycle.rule, [
+      bucket.setMetadata = (metadata: BucketMetadata) => {
+        assert.deepStrictEqual(metadata.lifecycle?.rule, [
           {
             action: {
-              type: rule.action.charAt(0).toUpperCase() + rule.action.slice(1),
+              type: 'Delete',
             },
             condition: rule.condition,
           },
@@ -557,10 +516,10 @@ describe('Bucket', () => {
         },
       };
 
-      bucket.setMetadata = (metadata: Metadata) => {
+      bucket.setMetadata = (metadata: BucketMetadata) => {
         const expectedDateString = date.toISOString().replace(/T.+$/, '');
 
-        const rule = metadata.lifecycle.rule[0];
+        const rule = metadata!.lifecycle!.rule![0];
         assert.strictEqual(rule.condition.createdBefore, expectedDateString);
 
         done();
@@ -585,9 +544,9 @@ describe('Bucket', () => {
         done(new Error('Metadata should not be refreshed.'));
       };
 
-      bucket.setMetadata = (metadata: Metadata) => {
-        assert.strictEqual(metadata.lifecycle.rule.length, 1);
-        assert.deepStrictEqual(metadata.lifecycle.rule, [rule]);
+      bucket.setMetadata = (metadata: BucketMetadata) => {
+        assert.strictEqual(metadata!.lifecycle!.rule!.length, 1);
+        assert.deepStrictEqual(metadata.lifecycle?.rule, [rule]);
         done();
       };
 
@@ -595,16 +554,16 @@ describe('Bucket', () => {
     });
 
     it('should combine rule with existing rules by default', done => {
-      const existingRule = {
+      const existingRule: LifecycleRule = {
         action: {
-          type: 'type',
+          type: 'Delete',
         },
         condition: {},
       };
 
-      const newRule = {
+      const newRule: LifecycleRule = {
         action: {
-          type: 'type',
+          type: 'Delete',
         },
         condition: {},
       };
@@ -613,9 +572,9 @@ describe('Bucket', () => {
         callback(null, {lifecycle: {rule: [existingRule]}}, {});
       };
 
-      bucket.setMetadata = (metadata: Metadata) => {
-        assert.strictEqual(metadata.lifecycle.rule.length, 2);
-        assert.deepStrictEqual(metadata.lifecycle.rule, [
+      bucket.setMetadata = (metadata: BucketMetadata) => {
+        assert.strictEqual(metadata!.lifecycle!.rule!.length, 2);
+        assert.deepStrictEqual(metadata.lifecycle?.rule, [
           existingRule,
           newRule,
         ]);
@@ -626,23 +585,23 @@ describe('Bucket', () => {
     });
 
     it('should accept multiple rules', done => {
-      const existingRule = {
+      const existingRule: LifecycleRule = {
         action: {
-          type: 'type',
+          type: 'Delete',
         },
         condition: {},
       };
 
-      const newRules = [
+      const newRules: LifecycleRule[] = [
         {
           action: {
-            type: 'type',
+            type: 'Delete',
           },
           condition: {},
         },
         {
           action: {
-            type: 'type2',
+            type: 'Delete',
           },
           condition: {},
         },
@@ -652,9 +611,9 @@ describe('Bucket', () => {
         callback(null, {lifecycle: {rule: [existingRule]}}, {});
       };
 
-      bucket.setMetadata = (metadata: Metadata) => {
-        assert.strictEqual(metadata.lifecycle.rule.length, 3);
-        assert.deepStrictEqual(metadata.lifecycle.rule, [
+      bucket.setMetadata = (metadata: BucketMetadata) => {
+        assert.strictEqual(metadata!.lifecycle!.rule!.length, 3);
+        assert.deepStrictEqual(metadata.lifecycle?.rule, [
           existingRule,
           newRules[0],
           newRules[1],
@@ -1649,7 +1608,7 @@ describe('Bucket', () => {
     });
 
     it('should update the logging metadata configuration', done => {
-      bucket.setMetadata = (metadata: Metadata) => {
+      bucket.setMetadata = (metadata: BucketMetadata) => {
         assert.deepStrictEqual(metadata.logging, {
           logBucket: bucket.id,
           logObjectPrefix: PREFIX,
@@ -1664,8 +1623,8 @@ describe('Bucket', () => {
     it('should allow a custom bucket to be provided', done => {
       const bucketName = 'bucket-name';
 
-      bucket.setMetadata = (metadata: Metadata) => {
-        assert.deepStrictEqual(metadata.logging.logBucket, bucketName);
+      bucket.setMetadata = (metadata: BucketMetadata) => {
+        assert.deepStrictEqual(metadata!.logging!.logBucket, bucketName);
         setImmediate(done);
         return Promise.resolve([]);
       };
@@ -1682,8 +1641,11 @@ describe('Bucket', () => {
     it('should accept a Bucket object', done => {
       const bucketForLogging = new Bucket(STORAGE, 'bucket-name');
 
-      bucket.setMetadata = (metadata: Metadata) => {
-        assert.deepStrictEqual(metadata.logging.logBucket, bucketForLogging.id);
+      bucket.setMetadata = (metadata: BucketMetadata) => {
+        assert.deepStrictEqual(
+          metadata!.logging!.logBucket,
+          bucketForLogging.id
+        );
         setImmediate(done);
         return Promise.resolve([]);
       };
@@ -2513,7 +2475,7 @@ describe('Bucket', () => {
     it('should correctly call setMetadata', done => {
       const labels = {};
       bucket.setMetadata = (
-        metadata: Metadata,
+        metadata: BucketMetadata,
         _callbackOrOptions: {},
         callback: Function
       ) => {
@@ -2545,7 +2507,7 @@ describe('Bucket', () => {
       ) => {
         assert.deepStrictEqual(metadata, {
           retentionPolicy: {
-            retentionPeriod: duration,
+            retentionPeriod: `${duration}`,
           },
         });
 
@@ -2582,7 +2544,7 @@ describe('Bucket', () => {
     const CALLBACK = util.noop;
 
     it('should convert camelCase to snake_case', done => {
-      bucket.setMetadata = (metadata: Metadata) => {
+      bucket.setMetadata = (metadata: BucketMetadata) => {
         assert.strictEqual(metadata.storageClass, 'CAMEL_CASE');
         done();
       };
@@ -2591,7 +2553,7 @@ describe('Bucket', () => {
     });
 
     it('should convert hyphenate to snake_case', done => {
-      bucket.setMetadata = (metadata: Metadata) => {
+      bucket.setMetadata = (metadata: BucketMetadata) => {
         assert.strictEqual(metadata.storageClass, 'HYPHENATED_CLASS');
         done();
       };
@@ -2601,7 +2563,7 @@ describe('Bucket', () => {
 
     it('should call setMetdata correctly', () => {
       bucket.setMetadata = (
-        metadata: Metadata,
+        metadata: BucketMetadata,
         options: {},
         callback: Function
       ) => {
@@ -2663,7 +2625,7 @@ describe('Bucket', () => {
     };
 
     beforeEach(() => {
-      bucket.file = (name: string, metadata: Metadata) => {
+      bucket.file = (name: string, metadata: FileMetadata) => {
         return new FakeFile(bucket, name, metadata);
       };
     });
@@ -2999,7 +2961,7 @@ describe('Bucket', () => {
         ws.write = () => true;
         setImmediate(() => {
           assert.strictEqual(
-            options.metadata.contentType,
+            options!.metadata!.contentType,
             metadata.contentType
           );
           done();
diff --git a/test/channel.ts b/test/channel.ts
index e14d4ed1fb..b671f0ae26 100644
--- a/test/channel.ts
+++ b/test/channel.ts
@@ -17,6 +17,7 @@
  */
 
 import {
+  BaseMetadata,
   DecorateRequestOptions,
   ServiceObject,
   ServiceObjectConfig,
@@ -34,7 +35,7 @@ const fakePromisify = {
   },
 };
 
-class FakeServiceObject extends ServiceObject {
+class FakeServiceObject extends ServiceObject<FakeServiceObject, BaseMetadata> {
   calledWith_: IArguments;
   constructor(config: ServiceObjectConfig) {
     super(config);
diff --git a/test/file.ts b/test/file.ts
index 14b493f229..d79e4b7ad0 100644
--- a/test/file.ts
+++ b/test/file.ts
@@ -16,7 +16,6 @@ import {
   ApiError,
   BodyResponseCallback,
   DecorateRequestOptions,
-  Metadata,
   MetadataCallback,
   ServiceObject,
   ServiceObjectConfig,
@@ -53,10 +52,14 @@ import {
   STORAGE_POST_POLICY_BASE_URL,
   MoveOptions,
   FileExceptionMessages,
+  FileMetadata,
 } from '../src/file';
 import {ExceptionMessages, IdempotencyStrategy} from '../src/storage';
 import {formatAsUTCISO} from '../src/util';
-import {SetMetadataOptions} from '../src/nodejs-common/service-object';
+import {
+  BaseMetadata,
+  SetMetadataOptions,
+} from '../src/nodejs-common/service-object';
 
 class HTTPError extends Error {
   code: number;
@@ -150,7 +153,7 @@ Object.assign(fakeResumableUpload, {
   },
 });
 
-class FakeServiceObject extends ServiceObject {
+class FakeServiceObject extends ServiceObject<FakeServiceObject, BaseMetadata> {
   calledWith_: IArguments;
   constructor(config: ServiceObjectConfig) {
     super(config);
@@ -3683,9 +3686,9 @@ describe('File', () => {
       const apiResponse = {};
 
       file.setMetadata = (
-        metadata: Metadata,
-        optionsOrCallback: SetMetadataOptions | MetadataCallback,
-        cb: MetadataCallback
+        metadata: FileMetadata,
+        optionsOrCallback: SetMetadataOptions | MetadataCallback<FileMetadata>,
+        cb: MetadataCallback<FileMetadata>
       ) => {
         Promise.resolve([apiResponse]).then(resp => cb(null, ...resp));
       };
diff --git a/test/hmacKey.ts b/test/hmacKey.ts
index 9ceb342a4e..1f5b8b1566 100644
--- a/test/hmacKey.ts
+++ b/test/hmacKey.ts
@@ -16,8 +16,8 @@ import * as sinon from 'sinon';
 import * as proxyquire from 'proxyquire';
 import * as assert from 'assert';
 import {describe, it, beforeEach, afterEach} from 'mocha';
-import {util, ServiceObject, Metadata} from '../src/nodejs-common';
-import {IdempotencyStrategy} from '../src';
+import {util, ServiceObject} from '../src/nodejs-common';
+import {HmacKeyMetadata, IdempotencyStrategy} from '../src';
 
 const sandbox = sinon.createSandbox();
 // eslint-disable-next-line @typescript-eslint/no-explicit-any
@@ -98,7 +98,7 @@ describe('HmacKey', () => {
     });
 
     it('should correctly call setMetadata', done => {
-      hmacKey.setMetadata = (metadata: Metadata, callback: Function) => {
+      hmacKey.setMetadata = (metadata: HmacKeyMetadata, callback: Function) => {
         assert.deepStrictEqual(metadata.accessId, ACCESS_ID);
         Promise.resolve([]).then(resp => callback(null, ...resp));
       };
diff --git a/test/index.ts b/test/index.ts
index 3b8b07c30f..7b592abf4a 100644
--- a/test/index.ts
+++ b/test/index.ts
@@ -15,7 +15,6 @@
 import {
   ApiError,
   DecorateRequestOptions,
-  Metadata,
   Service,
   ServiceConfig,
   util,
@@ -835,7 +834,7 @@ describe('Storage', () => {
       };
       storage.createBucket(
         BUCKET_NAME,
-        (err: Error, bucket: Bucket, apiResponse: Metadata) => {
+        (err: Error, bucket: Bucket, apiResponse: unknown) => {
           assert.strictEqual(resp, apiResponse);
           done();
         }
@@ -1026,7 +1025,7 @@ describe('Storage', () => {
 
       storage.getBuckets(
         {},
-        (err: Error, buckets: Bucket[], nextQuery: {}, resp: Metadata) => {
+        (err: Error, buckets: Bucket[], nextQuery: {}, resp: unknown) => {
           assert.strictEqual(err, error);
           assert.strictEqual(buckets, null);
           assert.strictEqual(nextQuery, null);
@@ -1193,7 +1192,7 @@ describe('Storage', () => {
 
       storage.getHmacKeys(
         {},
-        (err: Error, hmacKeys: HmacKey[], nextQuery: {}, resp: Metadata) => {
+        (err: Error, hmacKeys: HmacKey[], nextQuery: {}, resp: unknown) => {
           assert.strictEqual(err, error);
           assert.strictEqual(hmacKeys, null);
           assert.strictEqual(nextQuery, null);
@@ -1244,7 +1243,7 @@ describe('Storage', () => {
       });
 
       storage.getHmacKeys(
-        (err: Error, _hmacKeys: [], _nextQuery: {}, apiResponse: Metadata) => {
+        (err: Error, _hmacKeys: [], _nextQuery: {}, apiResponse: unknown) => {
           assert.ifError(err);
           assert.deepStrictEqual(resp, apiResponse);
           done();
@@ -1310,7 +1309,7 @@ describe('Storage', () => {
 
       it('should return the error and apiResponse', done => {
         storage.getServiceAccount(
-          (err: Error, serviceAccount: {}, apiResponse: Metadata) => {
+          (err: Error, serviceAccount: {}, apiResponse: unknown) => {
             assert.strictEqual(err, ERROR);
             assert.strictEqual(serviceAccount, null);
             assert.strictEqual(apiResponse, API_RESPONSE);
diff --git a/test/nodejs-common/service-object.ts b/test/nodejs-common/service-object.ts
index 518c08a5e9..c2be0f912f 100644
--- a/test/nodejs-common/service-object.ts
+++ b/test/nodejs-common/service-object.ts
@@ -63,12 +63,14 @@ interface InternalServiceObject {
   interceptors: SO.Interceptor[];
 }
 
-function asInternal(serviceObject: SO.ServiceObject) {
+function asInternal(
+  serviceObject: SO.ServiceObject<InternalServiceObject, SO.BaseMetadata>
+) {
   return serviceObject as {} as InternalServiceObject;
 }
 
 describe('ServiceObject', () => {
-  let serviceObject: SO.ServiceObject<FakeServiceObject>;
+  let serviceObject: SO.ServiceObject<FakeServiceObject, SO.BaseMetadata>;
   const sandbox = sinon.createSandbox();
 
   const CONFIG = {
@@ -293,10 +295,12 @@ describe('ServiceObject', () => {
       sandbox
         .stub(ServiceObject.prototype, 'request')
         .callsFake((reqOpts, callback) => {
-          assert.strictEqual(reqOpts.method, 'DELETE');
-          assert.strictEqual(reqOpts.uri, '');
+          const opts = reqOpts as r.OptionsWithUri;
+          const cb = callback as BodyResponseCallback;
+          assert.strictEqual(opts.method, 'DELETE');
+          assert.strictEqual(opts.uri, '');
           done();
-          callback(null, null, {} as r.Response);
+          cb(null, null, {} as r.Response);
         });
       serviceObject.delete(assert.ifError);
     });
@@ -306,9 +310,11 @@ describe('ServiceObject', () => {
       sandbox
         .stub(ServiceObject.prototype, 'request')
         .callsFake((reqOpts, callback) => {
-          assert.deepStrictEqual(reqOpts.qs, options);
+          const opts = reqOpts as r.OptionsWithUri;
+          const cb = callback as BodyResponseCallback;
+          assert.deepStrictEqual(opts.qs, options);
           done();
-          callback(null, null, {} as r.Response);
+          cb(null, null, {} as r.Response);
         });
       serviceObject.delete(options, assert.ifError);
     });
@@ -325,15 +331,17 @@ describe('ServiceObject', () => {
 
       sandbox
         .stub(ServiceObject.prototype, 'request')
-        .callsFake((reqOpts_, callback) => {
+        .callsFake((reqOpts, callback) => {
+          const opts = reqOpts as r.OptionsWithUri;
+          const cb = callback as BodyResponseCallback;
           assert.deepStrictEqual(
             serviceObject.methods.delete,
             cachedMethodConfig
           );
-          assert.deepStrictEqual(reqOpts_.uri, 'v2');
-          assert.deepStrictEqual(reqOpts_.method, 'PATCH');
+          assert.deepStrictEqual(opts.uri, 'v2');
+          assert.deepStrictEqual(opts.method, 'PATCH');
           done();
-          callback(null, null, null!);
+          cb(null, null, null!);
         });
 
       const serviceObject = new ServiceObject(CONFIG) as FakeServiceObject;
@@ -368,9 +376,11 @@ describe('ServiceObject', () => {
       sandbox
         .stub(ServiceObject.prototype, 'request')
         .callsFake((reqOpts, callback) => {
-          assert.strictEqual(reqOpts.qs.ignoreNotFound, undefined);
+          const opts = reqOpts as r.OptionsWithUri;
+          const cb = callback as BodyResponseCallback;
+          assert.strictEqual(opts.qs.ignoreNotFound, undefined);
           done();
-          callback(null, null, {} as r.Response);
+          cb(null, null, {} as r.Response);
         });
       serviceObject.delete(options, assert.ifError);
     });
@@ -389,18 +399,20 @@ describe('ServiceObject', () => {
 
       sandbox
         .stub(ServiceObject.prototype, 'request')
-        .callsFake((reqOpts_, callback) => {
+        .callsFake((reqOpts, callback) => {
+          const opts = reqOpts as r.OptionsWithUri;
+          const cb = callback as BodyResponseCallback;
           assert.deepStrictEqual(
             serviceObject.methods.delete,
             cachedMethodConfig
           );
-          assert.deepStrictEqual(reqOpts_.qs, {
+          assert.deepStrictEqual(opts.qs, {
             defaultProperty: true,
             optionalProperty: true,
             thisPropertyWasOverridden: true,
           });
           done();
-          callback(null, null, null!);
+          cb(null, null, null!);
         });
 
       const serviceObject = new ServiceObject(CONFIG) as FakeServiceObject;
@@ -442,10 +454,12 @@ describe('ServiceObject', () => {
       const options = {queryOptionProperty: true};
       sandbox
         .stub(ServiceObject.prototype, 'get')
-        .callsFake((options_, callback) => {
-          assert.deepStrictEqual(options_, options);
+        .callsFake((reqOpts, callback) => {
+          const opts = reqOpts as r.OptionsWithUri;
+          const cb = callback as BodyResponseCallback;
+          assert.deepStrictEqual(opts, options);
           done();
-          callback(null, null, {} as r.Response);
+          cb(null, null, {} as r.Response);
         });
       serviceObject.exists(options, assert.ifError);
     });
@@ -511,10 +525,13 @@ describe('ServiceObject', () => {
 
     it('should execute callback with error & metadata', done => {
       const error = new Error('Error.');
-      const metadata = {} as SO.Metadata;
+      const metadata = {} as SO.BaseMetadata;
 
       serviceObject.getMetadata = promisify(
-        (options: SO.GetMetadataOptions, callback: SO.MetadataCallback) => {
+        (
+          options: SO.GetMetadataOptions,
+          callback: SO.MetadataCallback<SO.BaseMetadata>
+        ) => {
           callback(error, metadata);
         }
       );
@@ -529,10 +546,13 @@ describe('ServiceObject', () => {
     });
 
     it('should execute callback with instance & metadata', done => {
-      const metadata = {} as SO.Metadata;
+      const metadata = {} as SO.BaseMetadata;
 
       serviceObject.getMetadata = promisify(
-        (options: SO.GetMetadataOptions, callback: SO.MetadataCallback) => {
+        (
+          options: SO.GetMetadataOptions,
+          callback: SO.MetadataCallback<SO.BaseMetadata>
+        ) => {
           callback(null, metadata);
         }
       );
@@ -552,7 +572,7 @@ describe('ServiceObject', () => {
 
       const ERROR = new ApiError('bad');
       ERROR.code = 404;
-      const METADATA = {} as SO.Metadata;
+      const METADATA = {} as SO.BaseMetadata;
 
       beforeEach(() => {
         AUTO_CREATE_CONFIG = {
@@ -560,7 +580,10 @@ describe('ServiceObject', () => {
         };
 
         serviceObject.getMetadata = promisify(
-          (options: SO.GetMetadataOptions, callback: SO.MetadataCallback) => {
+          (
+            options: SO.GetMetadataOptions,
+            callback: SO.MetadataCallback<SO.BaseMetadata>
+          ) => {
             callback(ERROR, METADATA);
           }
         );
@@ -644,11 +667,17 @@ describe('ServiceObject', () => {
     it('should make the correct request', done => {
       sandbox
         .stub(ServiceObject.prototype, 'request')
-        .callsFake(function (this: SO.ServiceObject, reqOpts, callback) {
+        .callsFake(function (
+          this: SO.ServiceObject<FakeServiceObject, SO.BaseMetadata>,
+          reqOpts,
+          callback
+        ) {
+          const opts = reqOpts as r.OptionsWithUri;
+          const cb = callback as BodyResponseCallback;
           assert.strictEqual(this, serviceObject);
-          assert.strictEqual(reqOpts.uri, '');
+          assert.strictEqual(opts.uri, '');
           done();
-          callback(null, null, {} as r.Response);
+          cb(null, null, {} as r.Response);
         });
       serviceObject.getMetadata(() => {});
     });
@@ -658,9 +687,11 @@ describe('ServiceObject', () => {
       sandbox
         .stub(ServiceObject.prototype, 'request')
         .callsFake((reqOpts, callback) => {
-          assert.deepStrictEqual(reqOpts.qs, options);
+          const opts = reqOpts as r.OptionsWithUri;
+          const cb = callback as BodyResponseCallback;
+          assert.deepStrictEqual(opts.qs, options);
           done();
-          callback(null, null, {} as r.Response);
+          cb(null, null, {} as r.Response);
         });
       serviceObject.getMetadata(options, assert.ifError);
     });
@@ -676,14 +707,16 @@ describe('ServiceObject', () => {
 
       sandbox
         .stub(ServiceObject.prototype, 'request')
-        .callsFake((reqOpts_, callback) => {
+        .callsFake((reqOpts, callback) => {
+          const opts = reqOpts as r.OptionsWithUri;
+          const cb = callback as BodyResponseCallback;
           assert.deepStrictEqual(
             serviceObject.methods.getMetadata,
             cachedMethodConfig
           );
-          assert.deepStrictEqual(reqOpts_.uri, 'v2');
+          assert.deepStrictEqual(opts.uri, 'v2');
           done();
-          callback(null, null, null!);
+          cb(null, null, null!);
         });
 
       const serviceObject = new ServiceObject(CONFIG) as FakeServiceObject;
@@ -705,18 +738,20 @@ describe('ServiceObject', () => {
 
       sandbox
         .stub(ServiceObject.prototype, 'request')
-        .callsFake((reqOpts_, callback) => {
+        .callsFake((reqOpts, callback) => {
+          const opts = reqOpts as r.OptionsWithUri;
+          const cb = callback as BodyResponseCallback;
           assert.deepStrictEqual(
             serviceObject.methods.getMetadata,
             cachedMethodConfig
           );
-          assert.deepStrictEqual(reqOpts_.qs, {
+          assert.deepStrictEqual(opts.qs, {
             defaultProperty: true,
             optionalProperty: true,
             thisPropertyWasOverridden: true,
           });
           done();
-          callback(null, null, null!);
+          cb(null, null, null!);
         });
 
       const serviceObject = new ServiceObject(CONFIG) as FakeServiceObject;
@@ -860,13 +895,19 @@ describe('ServiceObject', () => {
       const metadata = {metadataProperty: true};
       sandbox
         .stub(ServiceObject.prototype, 'request')
-        .callsFake(function (this: SO.ServiceObject, reqOpts, callback) {
+        .callsFake(function (
+          this: SO.ServiceObject<FakeServiceObject, SO.BaseMetadata>,
+          reqOpts,
+          callback
+        ) {
+          const opts = reqOpts as r.OptionsWithUri;
+          const cb = callback as BodyResponseCallback;
           assert.strictEqual(this, serviceObject);
-          assert.strictEqual(reqOpts.method, 'PATCH');
-          assert.strictEqual(reqOpts.uri, '');
-          assert.deepStrictEqual(reqOpts.json, metadata);
+          assert.strictEqual(opts.method, 'PATCH');
+          assert.strictEqual(opts.uri, '');
+          assert.deepStrictEqual(opts.json, metadata);
           done();
-          callback(null, null, {} as r.Response);
+          cb(null, null, {} as r.Response);
         });
       serviceObject.setMetadata(metadata, () => {});
     });
@@ -877,9 +918,11 @@ describe('ServiceObject', () => {
       sandbox
         .stub(ServiceObject.prototype, 'request')
         .callsFake((reqOpts, callback) => {
-          assert.deepStrictEqual(reqOpts.qs, options);
+          const opts = reqOpts as r.OptionsWithUri;
+          const cb = callback as BodyResponseCallback;
+          assert.deepStrictEqual(opts.qs, options);
           done();
-          callback(null, null, {} as r.Response);
+          cb(null, null, {} as r.Response);
         });
       serviceObject.setMetadata(metadata, options, () => {});
     });
@@ -895,15 +938,17 @@ describe('ServiceObject', () => {
 
       sandbox
         .stub(ServiceObject.prototype, 'request')
-        .callsFake((reqOpts_, callback) => {
+        .callsFake((reqOpts, callback) => {
+          const opts = reqOpts as r.OptionsWithUri;
+          const cb = callback as BodyResponseCallback;
           assert.deepStrictEqual(
             serviceObject.methods.setMetadata,
             cachedMethodConfig
           );
-          assert.deepStrictEqual(reqOpts_.uri, 'v2');
-          assert.deepStrictEqual(reqOpts_.method, 'PUT');
+          assert.deepStrictEqual(opts.uri, 'v2');
+          assert.deepStrictEqual(opts.method, 'PUT');
           done();
-          callback(null, null, null!);
+          cb(null, null, null!);
         });
 
       const serviceObject = new ServiceObject(CONFIG) as FakeServiceObject;
@@ -924,18 +969,20 @@ describe('ServiceObject', () => {
 
       sandbox
         .stub(ServiceObject.prototype, 'request')
-        .callsFake((reqOpts_, callback) => {
+        .callsFake((reqOpts, callback) => {
+          const opts = reqOpts as r.OptionsWithUri;
+          const cb = callback as BodyResponseCallback;
           assert.deepStrictEqual(
             serviceObject.methods.setMetadata,
             cachedMethodConfig
           );
-          assert.deepStrictEqual(reqOpts_.qs, {
+          assert.deepStrictEqual(opts.qs, {
             defaultProperty: true,
             optionalProperty: true,
             thisPropertyWasOverridden: true,
           });
           done();
-          callback(null, null, null!);
+          cb(null, null, null!);
         });
 
       const serviceObject = new ServiceObject(CONFIG) as FakeServiceObject;
@@ -1082,7 +1129,10 @@ describe('ServiceObject', () => {
       });
 
       sandbox
-        .stub(parent.parent as SO.ServiceObject, 'request')
+        .stub(
+          parent.parent as SO.ServiceObject<FakeServiceObject, SO.BaseMetadata>,
+          'request'
+        )
         .callsFake((reqOpts, callback) => {
           assert.deepStrictEqual(
             reqOpts.interceptors_![0].request({} as DecorateRequestOptions),
diff --git a/test/notification.ts b/test/notification.ts
index e986f69dbb..1847612890 100644
--- a/test/notification.ts
+++ b/test/notification.ts
@@ -13,6 +13,7 @@
 // limitations under the License.
 
 import {
+  BaseMetadata,
   DecorateRequestOptions,
   ServiceObject,
   ServiceObjectConfig,
@@ -24,7 +25,7 @@ import * as proxyquire from 'proxyquire';
 
 import {Bucket} from '../src';
 
-class FakeServiceObject extends ServiceObject {
+class FakeServiceObject extends ServiceObject<FakeServiceObject, BaseMetadata> {
   calledWith_: IArguments;
   constructor(config: ServiceObjectConfig) {
     super(config);
@@ -51,6 +52,10 @@ describe('Notification', () => {
 
   const BUCKET = {
     createNotification: fakeUtil.noop,
+    // eslint-disable-next-line @typescript-eslint/no-unused-vars
+    request(_reqOpts: DecorateRequestOptions, _callback: Function) {
+      return fakeUtil.noop();
+    },
   };
 
   const ID = '123';
@@ -67,6 +72,7 @@ describe('Notification', () => {
 
   beforeEach(() => {
     BUCKET.createNotification = fakeUtil.noop = () => {};
+    BUCKET.request = fakeUtil.noop = () => {};
     notification = new Notification(BUCKET, ID);
   });
 
@@ -86,6 +92,21 @@ describe('Notification', () => {
 
       assert.deepStrictEqual(calledWith.methods, {
         create: true,
+        delete: {
+          reqOpts: {
+            qs: {},
+          },
+        },
+        get: {
+          reqOpts: {
+            qs: {},
+          },
+        },
+        getMetadata: {
+          reqOpts: {
+            qs: {},
+          },
+        },
         exists: true,
       });
     });
@@ -117,13 +138,13 @@ describe('Notification', () => {
     it('should make the correct request', done => {
       const options = {};
 
-      notification.request = (
+      BUCKET.request = (
         reqOpts: DecorateRequestOptions,
         callback: Function
       ) => {
         assert.strictEqual(reqOpts.method, 'DELETE');
-        assert.strictEqual(reqOpts.uri, '');
-        assert.strictEqual(reqOpts.qs, options);
+        assert.strictEqual(reqOpts.uri, 'notificationConfigs/123');
+        assert.deepStrictEqual(reqOpts.qs, options);
         callback(); // the done fn
       };
 
@@ -131,7 +152,7 @@ describe('Notification', () => {
     });
 
     it('should optionally accept options', done => {
-      notification.request = (
+      BUCKET.request = (
         reqOpts: DecorateRequestOptions,
         callback: Function
       ) => {
@@ -143,16 +164,14 @@ describe('Notification', () => {
     });
 
     it('should optionally accept a callback', done => {
-      fakeUtil.noop = done;
-
-      notification.request = (
-        reqOpts: DecorateRequestOptions,
+      BUCKET.request = (
+        _reqOpts: DecorateRequestOptions,
         callback: Function
       ) => {
         callback(); // the done fn
       };
 
-      notification.delete();
+      notification.delete(done);
     });
   });
 
@@ -169,7 +188,7 @@ describe('Notification', () => {
       const options = {};
 
       notification.getMetadata = (options_: {}) => {
-        assert.strictEqual(options_, options);
+        assert.deepStrictEqual(options_, options);
         done();
       };
 
@@ -180,7 +199,7 @@ describe('Notification', () => {
       const error = new Error('Error.');
       const metadata = {};
 
-      notification.getMetadata = (options: {}, callback: Function) => {
+      notification.getMetadata = (_options: {}, callback: Function) => {
         callback(error, metadata);
       };
 
@@ -196,7 +215,7 @@ describe('Notification', () => {
     it('should execute callback with instance & metadata', done => {
       const metadata = {};
 
-      notification.getMetadata = (options: {}, callback: Function) => {
+      notification.getMetadata = (_options: {}, callback: Function) => {
         callback(null, metadata);
       };
 
@@ -221,22 +240,25 @@ describe('Notification', () => {
           autoCreate: true,
         };
 
-        notification.getMetadata = (options: {}, callback: Function) => {
+        notification.getMetadata = (_options: {}, callback: Function) => {
           callback(ERROR, METADATA);
         };
       });
 
       it('should pass config to create if it was provided', done => {
-        const config = Object.assign({}, AUTO_CREATE_CONFIG, {
-          maxResults: 5,
-        });
-
-        notification.create = (config_: {}) => {
-          assert.strictEqual(config_, config);
+        const config = Object.assign(
+          {},
+          {
+            maxResults: 5,
+          }
+        );
+
+        notification.get = (config_: {}) => {
+          assert.deepStrictEqual(config_, config);
           done();
         };
 
-        notification.get(config, assert.ifError);
+        notification.get(config);
       });
 
       it('should pass only a callback to create if no config', done => {
@@ -296,9 +318,9 @@ describe('Notification', () => {
     it('should make the correct request', done => {
       const options = {};
 
-      notification.request = (reqOpts: DecorateRequestOptions) => {
-        assert.strictEqual(reqOpts.uri, '');
-        assert.strictEqual(reqOpts.qs, options);
+      BUCKET.request = (reqOpts: DecorateRequestOptions) => {
+        assert.strictEqual(reqOpts.uri, 'notificationConfigs/123');
+        assert.deepStrictEqual(reqOpts.qs, options);
         done();
       };
 
@@ -306,7 +328,7 @@ describe('Notification', () => {
     });
 
     it('should optionally accept options', done => {
-      notification.request = (reqOpts: DecorateRequestOptions) => {
+      BUCKET.request = (reqOpts: DecorateRequestOptions) => {
         assert.deepStrictEqual(reqOpts.qs, {});
         done();
       };
@@ -318,16 +340,16 @@ describe('Notification', () => {
       const error = new Error('err');
       const response = {};
 
-      notification.request = (
-        reqOpts: DecorateRequestOptions,
+      BUCKET.request = (
+        _reqOpts: DecorateRequestOptions,
         callback: Function
       ) => {
-        callback(error, response);
+        callback(error, response, response);
       };
 
       notification.getMetadata((err: Error, metadata: {}, resp: {}) => {
         assert.strictEqual(err, error);
-        assert.strictEqual(metadata, null);
+        assert.strictEqual(metadata, response);
         assert.strictEqual(resp, response);
         done();
       });
@@ -336,11 +358,11 @@ describe('Notification', () => {
     it('should set and return the metadata', done => {
       const response = {};
 
-      notification.request = (
-        reqOpts: DecorateRequestOptions,
+      BUCKET.request = (
+        _reqOpts: DecorateRequestOptions,
         callback: Function
       ) => {
-        callback(null, response);
+        callback(null, response, response);
       };
 
       notification.getMetadata((err: Error, metadata: {}, resp: {}) => {
diff --git a/test/transfer-manager.ts b/test/transfer-manager.ts
index be9d56cd2e..b64b456fbd 100644
--- a/test/transfer-manager.ts
+++ b/test/transfer-manager.ts
@@ -15,7 +15,12 @@
  */
 
 /* eslint-disable @typescript-eslint/no-explicit-any */
-import {ServiceObject, ServiceObjectConfig, util} from '../src/nodejs-common';
+import {
+  BaseMetadata,
+  ServiceObject,
+  ServiceObjectConfig,
+  util,
+} from '../src/nodejs-common';
 import * as pLimit from 'p-limit';
 import * as proxyquire from 'proxyquire';
 import {
@@ -32,11 +37,12 @@ import * as path from 'path';
 import * as stream from 'stream';
 import * as extend from 'extend';
 import * as fs from 'fs';
+import {FileMetadata} from '../src/file';
 
 const fakeUtil = Object.assign({}, util);
 fakeUtil.noop = util.noop;
 
-class FakeServiceObject extends ServiceObject {
+class FakeServiceObject extends ServiceObject<FakeServiceObject, BaseMetadata> {
   calledWith_: IArguments;
   constructor(config: ServiceObjectConfig) {
     super(config);
@@ -57,7 +63,7 @@ class FakeFile {
   bucket: Bucket;
   name: string;
   options: FileOptions;
-  metadata: {};
+  metadata: FileMetadata;
   createWriteStream: Function;
   isSameFile = () => false;
   constructor(bucket: Bucket, name: string, options?: FileOptions) {
@@ -69,7 +75,7 @@ class FakeFile {
     this.metadata = {};
 
     this.createWriteStream = (options: CreateWriteStreamOptions) => {
-      this.metadata = options.metadata;
+      this.metadata = options.metadata!;
       const ws = new stream.Writable();
       ws.write = () => {
         ws.emit('complete');