Improve AGENTS.md: fix misleading and broken content

[HeikoKlare]

Summary

• Remove broken/malformed build command that concatenated two mvn invocations into one invalid command line
• Remove a mvn clean test example that doesn't work in Tycho projects (tests require mvn verify)
• Rename "Critical Limitation" section to "Building Individual Bundles" for clarity
• Add missing instruction on how to include changed source bundles alongside test bundles in the -pl parameter
• Remove every information about -Pbuild-individual-bundles as it's already defined via .mvn/maven.config
• Restructure sections: merge scattered Testing/Common Development Commands content into coherent Build System and Development Hints sections; move "Finding test bundles" and JUnit guidelines next to related content
• Remove incorrect statement that Co-Authored-By trailers fail the Eclipse license check

Background

A key insight driving these changes: when running tests, agents were not including bundles containing modified classes in the -pl parameter alongside the test bundle. This caused tests to run against stale compiled code rather than the changes under test. The instructions now explicitly document the correct pattern:

mvn clean verify -pl :org.eclipse.jface,:org.eclipse.jface.tests

Note

These changes were developed together with a Claude Code agent to verify that the instructions are actually useful and unambiguous from an agent's perspective.

[vogella]

Minor nits:

• Grammar: "their bundles needs to be added" → "their bundles need to be added."
• The placeholder-ization (:TEST_BUNDLE_NAME instead of org.eclipse.ui.tests) is a wash. You wisely kept inline org.eclipse.jface.tests examples, so the teaching value survives; concrete-only would have been fine too.

[HeikoKlare]

Thank you for the hints. Both are fully valid. I have updated the PR accordingly, in particular removing the abstract command pattern and just preserving the examples (with proper prose where necessary).

[vogella]

Thanks, especially the working examples for the build are important, abstraction here is only hurtful.

[akurtakov]

I am not sure whether it is helpful or just adding noise but with

eclipse.platform.ui/.mvn/maven.config

Line 1 in b268df2

-Pbuild-individual-bundles

-Pbuild-individual-bundles parameter to most commands shouldn't be needed.

[HeikoKlare]

I am not sure whether it is helpful or just adding noise but with

eclipse.platform.ui/.mvn/maven.config

Line 1 in b268df2

-Pbuild-individual-bundles

-Pbuild-individual-bundles parameter to most commands shouldn't be needed.

Great hint, thank you. I wasn't aware of that configuration. I can confirm that passing the profile to maven commands is completely unnecessary. I have removed every information about that from the agents.md.