fix two problems in dubbo plugin

[CoderLan0668]

What does this PR do?

to fix two problem in dubbo plugin

• ensure that dubbo transaction will only be created at the provider side
• the apm headers will be covered with unexpected value when the application invoke a dubbo api within a dubbo transaction

Checklist

• [√] This is a bugfix
  • [√] I have updated CHANGELOG.asciidoc
  • [√] I have added tests that would fail without this fix

[cla-checker-service]

💚 CLA has been signed

[ghost]

💚 Build Succeeded

the below badges are clickable and redirect to their specific view in the CI or DOCS

Expand to view the summary

Build stats

• Start Time: 2022-01-18T20:17:54.455+0000

• Duration: 46 min 1 sec

• Commit: ee30ec6

Test stats 🧪

Test	Results
Failed	0
Passed	2446
Skipped	16
Total	2462

💚 Flaky test report

Tests succeeded.

🤖 GitHub comments

To re-run your PR in the CI, just comment with:

• /test : Re-trigger the build.

• run benchmark tests : Run the benchmark test.

• run compatibility tests : Run the JDK Compatibility test.

• run integration tests : Run the APM-ITs.

• run elasticsearch-ci/docs : Re-trigger the docs validation. (use unformatted text in the comment!)

[SylvainJuge]

/test

[CoderLan0668]

@SylvainJuge Can this PR be merged?

[CoderLan0668]

All tests are passed, So what‘s the problem with this PR? what can i do to make this pr to be merged early?

[CoderLan0668]

All tests are passed, So what‘s the problem with this PR? what can i do to make this pr to be merged early?

@SylvainJuge @AlexanderWert

[CoderLan0668]

All tests are passed, So what‘s the problem with this PR? what can i do to make this pr to be merged early?

@SylvainJuge @AlexanderWert

@felixbarny

[felixbarny]

Thanks a lot for your contribution and sorry for the radio silence. We have not forgotten about this PR but we're currently focussing on the tasks that we have planned for in the current milestone. I'm sorry that your PR didn't make it on that milestone. I'm adding it as a candidate for the next one.

[SylvainJuge]

I am really sorry it took us that long to get to this PR, as the changes are quite straightforward and properly covered with tests. Thanks a lot @CoderLan0668 ! When pushing to this branch I got a notification that it was renamed as dubbo_bak on your fork, are there other changes that we should include here ?

LGTM, I've taken the liberty to switch to using random test ports instead of static ones.

[SylvainJuge]

@elasticmachine run elasticsearch-ci/docs

[SylvainJuge]

@elasticmachine run elasticsearch-ci/docs