[Task]: Compile Java Examples Main on Java 11/17/21 when run Java Example Tests

[Abacn]

What would you like to happen?

Currently we run Java Examples in different Java versions (11, 17), e.g.

• https://ci-beam.apache.org/job/beam_PostCommit_Java_Examples_Dataflow_V2_java11/
• https://ci-beam.apache.org/job/beam_PostCommit_Java_Examples_Dataflow_V2_java17/
• https://github.com/apache/beam/blob/master/.github/workflows/beam_PostCommit_Java_Examples_Dataflow_Java.yml

In current tests (Jenkins, GHA Examples Dataflow v1), java home is always Java8, and it compile and run tests on Java 11/17, see

beam/.test-infra/jenkins/job_PostCommit_Java_Examples_Dataflow_V2_Java11.groovy

Line 48 in a94d29f

switches "-Pjava11Home=${commonJobProperties.JAVA_11_HOME}"

beam/.github/workflows/beam_PostCommit_Java_Examples_Dataflow_Java.yml

Lines 79 to 80 in a94d29f

	${{ matrix.java_version }}
	8

(note that GHA Examples Dataflow v2 currently just setup a single Java version, which is not quite aligned with this pattern)

However, the test scope source of :example:java project is really a thin wrapper for the examples, which live in main scope. This actually means the pipeline is compiled with Java8, then run with Java11/17 runtime, which is not quite we want (GHA Dataflow v2 accidentally compile all sources with Java11/17 though)

We should clean up current setting to make the Example test to

• all beam dependencies (e.g. Java core, runners) compile on Java 8 -- in alignment with released version
• examples main and test src compile with given Java version
• run test with given Java version

Issue Priority

Priority: 2 (default / most feature requests should be filed as P2)

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