[improvement,feature] Support groovy code with the annotation API:

[fredgalvao]

As per https://discuss.elastic.co/t/kibana-apm-not-showing-capturespan-and-capturetransaction/173026 and a few other tests I did myself in the last few weeks, apm-agent-java couldn't support code that went through groovyc with the annotation API (CaptureSpan, CaptureTransaction). I initially only saw that the annotations weren't making it to the final .class file, but couldn't investigate properly at the time.

It was only recently that I noticed that there was no RetentionPolicy for these two annotations, which was making the default RetentionPolicy#CLASS the chosen one, which can't really be seen during runtime by bytebuddy for things it doesn't fully understand. See this for more details on this, even though I can't really explain why bytebuddy would see it for java classes during runtime...

Changing the RetentionPolicy to RUNTIME enables everything I wanted and could test:

• tested on both:
  • grails[2.2.4], groovy[2.0.8]
  • grails[3.3.1], groovy[2.4.11]
• tested on both:
  • @CompileStatic
  • Normal(dynamic) compilation
• tested on both:
  • Spring components/artifacts
  • Raw code

Tests were already failing on my machine on master, so I really don't know if I could ever break anything with this change, but I'm willing to bet it will be inoffensive.

[ghost]

Hi @fredgalvao, we have found your signature in our records, but it seems like you have signed with a different e-mail than the one used in your Git commit. Can you please add both of these e-mails into your Github profile (they can be hidden), so we can match your e-mails to your Github profile?

[fredgalvao]

Sorry for the diff email thing. I've now fixed it.

[felixbarny]

Oh, boy, I can’t believe this oversight 🤦

Thanks a lot for investigating. I’m wondering how this has ever worked. While at it, could you also add the @Target(METHOD) annotation?

[codecov-io]

Codecov Report

Merging #567 into master will decrease coverage by 0.04%.
The diff coverage is 66.66%.

@@ Coverage Diff @@ ## master #567 +/- ## ============================================ - Coverage 62.19% 62.15% -0.05%  + Complexity 1264 68 -1196  ============================================ Files 185 185 Lines 6994 7002 +8 Branches 810 811 +1 ============================================ + Hits 4350 4352 +2  - Misses 2370 2374 +4  - Partials 274 276 +2

Impacted Files	Coverage Δ	Complexity Δ
...astic/apm/agent/configuration/ServiceNameUtil.java	77.27% <0%> (-3.68%)	0 <0> (-18)
...lastic/apm/agent/impl/transaction/Transaction.java	71.42% <0%> (-2.35%)	0 <0> (-21)
...ic/apm/agent/servlet/ServletTransactionHelper.java	76.22% <85.71%> (-0.76%)	0 <0> (ø)

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[fredgalvao]

My pleasure to help ;)

I’m wondering how this has ever worked.

#metoo

While at it, could you also add the @target(METHOD) annotation?

Done.