Independant module for test/jvm tools

[SylvainJuge]

We have some duplicated implementations of the following (non-exhaustive list, please add other relevant items if needed).

• [ ] (test) get a random available port (see usages of co.elastic.apm.agent.testutils.TestPort and javax.net.ServerSocketFactory#createServerSocket(int, int, java.net.InetAddress))
• [ ] (test) locate packaged artifacts from classpath/relative path (see co.elastic.apm.servlet.AgentFileAccessor#getTargetJar(java.lang.String, java.lang.String))
• [ ] find path to the JVM binary (getJavaBinaryPath).
• [ ] shutdown thread pools properly with co.elastic.apm.agent.util.ExecutorUtils, used both in tests and in production code.

Duplication is the the result of the following:

• not every module has a dependency on apm-agent-core hence code reuse is limited
• there is no root module that can host them

The goal would be to create one (or more) modules that provide

• all the test-only features in the test scope so it can be reused in any other module testing
• other items in the compile scope
• no dependency on other agent modules, only common libraries (slf4j, junit, ...).

[felixbarny]

I have recently introduced the apm-agent-common module. Maybe that's what you're looking for?

[SylvainJuge]

Yes, that sounds the perfect candidate to move those small utilities.