diff --git a/contributor-docs/code-change-guide.md b/contributor-docs/code-change-guide.md
index f0785d3509d0..b4300103454c 100644
--- a/contributor-docs/code-change-guide.md
+++ b/contributor-docs/code-change-guide.md
@@ -145,7 +145,7 @@ in the Google Cloud documentation.
 
 Depending on the languages involved, your `PATH` file needs to have the following elements configured.
 
-* A Java environment that uses a supported Java version, preferably Java 8.
+* A Java environment that uses a supported Java version, preferably Java 11.
   * This environment is needed for all development, because Beam is a Gradle project that uses JVM.
   * Recommended: To manage Java versions, use [sdkman](https://sdkman.io/install).
 
@@ -624,6 +624,11 @@ Tips for using the Dataflow runner:
 
 ## Appendix
 
+### Common Issues
+
+* If you run into some strange errors such as `java.lang.NoClassDefFoundError`, run `./gradlew clean` first
+* To run one single Java test with gradle, use `--tests` to filter, for example, `./gradlew :it:google-cloud-platform:WordCountIntegrationTest --tests "org.apache.beam.it.gcp.WordCountIT.testWordCountDataflow"`
+
 ### Directories of snapshot builds
 
 * https://repository.apache.org/content/groups/snapshots/org/apache/beam/ Java SDK build (nightly)