What's the meaning of 'sourceSets.all*'

Question

I'm new to gradle & groovy, and I don't know the exact meaning of such a statement:

sourceSets.all*.java

Is it a valid groovy expression?

Answer 1

It is a Groovy GPath expression. *. calls a property or method (java in this case) on every element in a collection (sourceSets.all in this case), and returns a collection of the results. In this case it will give you a collection of all Java SourceDirectorySets. In the case of reading a property (like here), the * can even be omitted.