Gradle dependencies cleanup

[iNikem]

Partially adresses #351 .

This PR touches mostly "shared" modules, like auto-bootstrap or java.gradle to allow for meaningful review. Later PR will change "leave" modules, where changes are very mechanical.

[tylerbenson]

I've always had a hard time understanding when to use gradle api vs implementation. Thanks for cleaning this up.

[iNikem]

But I don't understand why muzzle fails :(

[trask]

I think muzzle found a real issue. Not really sure why it didn't catch it before, probably your dependency cleanup revealed it somehow.

To make muzzle pass for now, go ahead and lie to it:

muzzle {
  pass {
    group = "io.opentracing.contrib.dropwizard"
    module = "dropwizard-opentracing"
    versions = "(,)"
    extraDependency 'io.opentelemetry:opentelemetry-contrib-auto-annotations:0.5.0'
  }
}

i think the "correct" way to deal with this is to split out the WithSpan instrumentation into a separate module, e.g. trask@a8e7e82

i'll turn this prototype into a follow-on PR after this one is merged

[iNikem]

@trask can you explain why current approach does not work? What is wrong with it?

[trask]

WithSpan should be treated like a third-party library that we are instrumenting, e.g.

https://github.com/trask/opentelemetry-java-instrumentation/blob/split-annotation-module/instrumentation/annotations/annotations-opentelemetry/annotations-opentelemetry.gradle#L4-L21

but instead we have a weird mix of treating it as a class we are instrumenting, but also as an internal class, e.g. we add it to the bootstrap classes in SpockRunner.java which is incorrect, and we relocate it in java-agent.gradle which is also incorrect.

[iNikem]

I see... Ok, I mostly understand, but why we have to split annotations instrumentation module? If we should treat WithSpan as any other third party library, why should be it separate from other annotations support?

[trask]

Oh, I think this is the way to go:

muzzle {
  pass {
    group = "io.opentelemetry"
    module = "opentelemetry-contrib-auto-annotations"
    versions = "(,)"
    extraDependency 'io.opentracing.contrib.dropwizard:dropwizard-opentracing:0.2.2'
  }
}

I was going to say it's better when there's only a single compile-time dependency in each instrumentation module (and that's the dependency we put in the muzzle block).

But then I realized that the trace-annotation module already only has one compile-time dependency, since WithSpan is the only annotation we take a compile-time dependency on.

We still need the extraDependency, because otherwise muzzle will say that TraceAnnotationsInstrumentation failed to match anything on the classpath.

[trask]

turned my comment above into a suggestion below