[java] Use single node for annotations

[oowekyala]

Grammar change is described below. This also makes Annotatable use node streams.

Annotations

• What: Annotations are consolidated into a single node. SingleMemberAnnotation, NormalAnnotation and MarkerAnnotation are removed in favour of Annotation. The Name node is removed.
• Why: Those different node types implement a syntax-only distinction, that only makes semantically equivalent annotations have different possible representations. For example, @A and @A() are semantically equivalent, yet they were parsed as MarkerAnnotation resp. NormalAnnotation. Similarly, @A("") and @A(value="") were parsed as SingleMemberAnnotation resp. NormalAnnotation. This also makes parsing much simpler.

Code	Old AST	New AST
@A	+ Annotation + MarkerAnnotation + Name "A"	+ Annotation "A"
@A()	+ Annotation + NormalAnnotation + Name "A"	+ Annotation + AnnotationMemberList
@A(value="v")	+ Annotation + NormalAnnotation + Name "A" + MemberValuePairs + MemberValuePair "value" + MemberValue + PrimaryExpression + PrimaryPrefix + Literal '"v"'	+ Annotation + AnnotationMemberList + MemberValuePair "value" [@Shorthand=false()] + StringLiteral '"v"'
@A("v")	+ Annotation + SingleMemberAnnotation + Name "A" + MemberValue + PrimaryExpression + PrimaryPrefix + Literal '"v"'	+ Annotation + AnnotationMemberList + MemberValuePair "value" [@Shorthand=true()] + StringLiteral '"v"'
@A(value="v", on=true)	+ Annotation + NormalAnnotation + Name "A" + MemberValuePairs + MemberValuePair "value" + MemberValue + PrimaryExpression + PrimaryPrefix + Literal '"v"' + MemberValuePair "on" + MemberValue + PrimaryExpression + PrimaryPrefix + Literal + BooleanLiteral [@True=true()]	+ Annotation + AnnotationMemberList + MemberValuePair "value" [@Shorthand=false()] + StringLiteral '"v"' + MemberValuePair "on" + BooleanLiteral [@True=true()]

[pmd-test]

	1 Message
📖	No java rules are changed!

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[adangel]

Interesting - this time without a setter. I've no strong opinion whether we should use jjtThis.setName(VoidName()) or jjtThis.name=VoidName()- whatever we do, we should do it the same in all other AST classes. Using a setter would provide us a bit more flexibility (although I don't know, whether we need/should use that - a setter should not contain too much logic...).

[oowekyala]

This is something I tried to make the grammar cleaner. But maybe, using a setter would be better, especially if the field is shared (this could be the image field)

[adangel]

Does this work, if it is declared here in ASTCastExpressionTest? I could imagine, this test needs to run before the others... This should probably be moved to the DSL in TestExtensions.kt

[oowekyala]

Toplevel functions and properties in kotlin are translated to static members of a class:
https://kotlinlang.org/docs/reference/java-to-kotlin-interop.html#package-level-functions

So this doesn't need to run. But for clarity, since this is used in several tests, it should indeed be put into TestExtensions.kt

[adangel]

Btw. Updated https://github.com/pmd/pmd/wiki/Java_clean_changes#annotations already