Create a Java code coverage example

baseline coverage is not supported in Bazel for C++. However it is not clear if it is fully working on Java or not.

This example would help to asses how is the bazel coverage in Bazel for Java and if the baseline coverage is supported or note.

Related Bazel issues:
https://github.com/bazelbuild/bazel/issues/5716
https://github.com/bazelbuild/bazel/issues/8324