RFR: 7861: Bump Agent build to Java 11 compliance and cleanup POM

Wed Jul 27 11:28:37 UTC 2022

The JMC Agent project is set up in a somewhat awkward way at the moment. The maven.compiler.source and maven.compiler.target properties are set to 1.8 but we enforce a JDK 11 during the build and also have a test case that implicitly uses/tests JDK11 features. Maybe it is time now to bump the agent to Java 11 compliance?

Furthermore, the POM file could be cleaned up and a few maven plugins that are used could be bumped to more recent versions.

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Commit messages:
 - Cleanup JMC agent pom

Changes: https://git.openjdk.org/jmc/pull/415/files
 Webrev: https://webrevs.openjdk.org/?repo=jmc&pr=415&range=00
  Issue: https://bugs.openjdk.org/browse/JMC-7861
  Stats: 214 lines in 3 files changed: 87 ins; 86 del; 41 mod
  Patch: https://git.openjdk.org/jmc/pull/415.diff
  Fetch: git fetch https://git.openjdk.org/jmc pull/415/head:pull/415

PR: https://git.openjdk.org/jmc/pull/415