Add the ability to rename annotations added by the Scala compiler.

[shawjef3]

This is for #146. I haven't tested the new functionality, but existing tests pass.

[shawjef3]

@johnrengelman The build failed due to a temporary godaddy failure. Please retrigger the build.

[johnrengelman]

Can you merge master to this. There’s a fix there.

[shawjef3]

@johnrengelman it passed. Thanks!

[shawjef3]

@johnrengelman I'm wondering if you've run into this. I want to use this patch with a project I have locally. I publish it.

./gradlew :publishPluginPublicationToMavenLocal

In my project I use pluginManagement in settings.gradle to have Gradle use my local published snapshot instead of the official Shadow publication. Then I run :shadowJar on my project. I get,

> Failed to apply plugin [class 'com.github.jengelman.gradle.plugins.shadow.ShadowJavaPlugin']
   > Could not create plugin of type 'ShadowJavaPlugin'.
      > The constructor for type ShadowJavaPlugin should be annotated with @Inject.

I looked at the class in the jar in my local repo, and it does have the annotation. However, when I debug Gradle's InjectUtil, the annotation is missing from the constructor. It's like Gradle's class loader is stripping it.

[shawjef3]

I also asked for help in the Gradle Slack.

[shawjef3]

I was able to use ((GeneratedClassImpl) type).generatedClass.getConstructors()[0].getAnnotations() to find that the actual annotation on the constructor is @shadow.javax.inject.Inject(). So it seems the publication is shadowing annotations.

[shawjef3]

I figured out what's happening. Something about my patch makes annotation classes be shaded also. This could be desirable but in this case it's not. I'll figure out how to make it only shade that Scala annotations.

[Goooler]

We should compat Kotlin as well, need further work like #1539.