Where is the exact implementation of the "java" plugin in the gradle source code?

Looking under:

/gradle/subprojects

I’ve seen that there us a ./language-jvm/src/main/groovy/org/gradle/language/java/ directory, however, I dont see where are the logic for the java plugin is (i.e. the src conventions, unit test invocations, etc).

Is the logic for the plugin spread around the source code in different areas?

In general, where is the code for the plugins that gradle builds with?

here you go

https://github.com/gradle/gradle/tree/master/subprojects/plugins/src/main/groovy/org/gradle/api/plugins