Groovy support for multiple assignment/tuple unpacking

[sudouser777]

1. Updated the groovy parser to support tuple unpacking.
2. closes Groovy parser fails with parentheses on the left-hand side of the assignment #5283 .

[sudouser777]

I have tried to hanlde the spaces situation, but it's tricky spaces are not being handled properly

    @Test
    void destructuringWithSpaces() {
        rewriteRun(
          groovy(
            """
              def ( key, value ) = "a1:b2".split(":")
              println(key)
              println(value)
              """
          )
        );
    }

Also static type also not working

  @Test
  void destructuringWithType() {
      rewriteRun(
        groovy(
          """
            def (String key, String value) = "a1:b2".split(":")
            println(key)
            println(value)
            """
        )
      );
  }

@greg-at-moderne I'm not sure if my approach is correct—open to any suggestions.

[shanman190]

This is usually a JContainer that holds the named variables, then wrapped inside of a J.Parentheses instead. This then means that the markers wouldn't be necessary.

[sudouser777]

But it's not including parenthesis, it's just returning JRightPadded<J.Identifier>

[shanman190]

This was more in general. The way to add parentheses around an element is with J.Parentheses and when that element is a list it is typically wrapped in a JContainer.

I'm not sure what elements you currently have in scope from the Groovy AST, but I'd expect that something similar would be the case here.

[sudouser777]

It's using the same J.VariableDeclarations for normal variable declarations. This will require changes to the J.VariableDeclarations class. I'm not entirely sure about this approach, though.

[timtebeek]

Thanks a lot for the continued improvements to the Groovy parser @sudouser777 ! Great to see steady progress being made.

Any reason you'd held off on a merge here @greg-at-moderne ?

[timtebeek]

Rather than adding new markers, is there any way we can make this work with regular J.Parentheses?

[sudouser777]

It's using J.VariableDeclarations, which is also used for normal variable declarations. If we add J.Parentheses, I'm not sure how many changes it would require in the existing code, and I'm also not sure whether it's possible to make the parentheses optional.

I'm open to suggestions—let me know if there's a better way we can handle this.

[greg-at-moderne]

Any reason you'd held off on a merge here @greg-at-moderne ?

No. I am good. I think this is good to be merged now.
Your comment on the PR is the only outstanding (minor) thing in my perspective.