Fixed the error message

docs/README.md

@@ -37,7 +37,7 @@ The following CSI interfaces are implemented:
 | az                  |        |   ""    | true      | Used for cross-account mount. `az` under storage class parameter is optional. If specified, mount target associated with the az will be used for cross-account mount. If not specified, a random mount target will be picked for cross account mount |
 
 **Notes**:
-* Custom Posix group Id range for Access Point root directory must include both `gidRangeStart` and `gidRangeEnd` parameters.
+* Custom Posix group Id range for Access Point root directory must include both `gidRangeStart` and `gidRangeEnd` parameters. These parameters are optional only if both are omitted. If you specify one, the other becomes mandatory.
 * When using a custom Posix group ID range, there is a possibility for the driver to run out of available POSIX group Ids. We suggest ensuring custom group ID range is large enough or create a new storage class with a new file system to provision additional volumes. 
 * `az` under storage class parameter is not be confused with efs-utils mount option `az`. The `az` mount option is used for cross-az mount or efs one zone file system mount within the same aws account as the cluster.
 

pkg/driver/controller.go

@@ -149,7 +149,7 @@ func (d *Driver) CreateVolume(ctx context.Context, req *csi.CreateVolumeRequest)
 	} else {
 		// Ensure GID max is provided with GID min
 		if gidMin != 0 {
-			return nil, status.Errorf(codes.InvalidArgument, "Missing %v parameter", GidMin)
+			return nil, status.Errorf(codes.InvalidArgument, "Missing %v parameter", GidMax)
 		}
 	}