A check to detect javadoc plugin malfunction #661
Description
Let's implement a check to detect javadoc plugin malfunction. We already have test, lint, and clirr jobs in https://github.com/googleapis/java-shared-config/blob/main/.github/workflows/downstream-maven-plugins.yaml.
@alicejli observed the following error:
Execution default-cli of goal org.apache.maven.plugins:maven-javadoc-plugin:3.6.0:aggregate failed: If a non-null excludes list is given, all elements must be non-null -> [Help 1]