Groovy parser does not support multiple closure arguments without parentheses

[jevanlingen]

Problem

Groovy let you omit the parentheses for function arguments. This does not work if you use multiple closures.

What is the smallest, simplest way to reproduce the problem?

@Test
void multipleClosureArguments() {
    rewriteRun(
        groovy(
           """
           def acceptsClosure(Closure a, Closure b) {}
           acceptsClosure { println(it) } {
               println(it)
            }
           """
        )
     );
 }

What did you expect to see?

A test that succeeds.

What did you see instead?

expected: 
  "def acceptsClosure(Closure a, Closure b) {}
  acceptsClosure { println(it) } {
      println(it)
  }"
 but was: 
  "def acceptsClosure(Closure a, Closure b) {}
  acceptsClosure { println(it) } ,
      {println(it)
  }"

Note

The groovy language is rather picky with omitting parentheses. For closures no comma is allowed, except when you join them with other types. So you need to define it like this, or it won't compile:

def acceptsClosure(Closure a, Closure b) {}
acceptsClosure { println(it) } { println(it) }

def functionX(String a, String b, String c, String d) {}
functionX "a", "b", "c", "d"

def combination(String a, Closure b, Closure c, String d) {}
combination "a", { println(it) }, { println(it) }, "d"

def combination2(Closure a, String d) {}
combination2({ println(it) }, "d") // starting with a closure seems not be possible without parentheses!