Consider the following:

class C {
  def  getX() { 'C' }
  void test() {
    [x:'map'].with {
      print getX()
    }
  }
}

"getX()" is declared by class C, not Map is this case (see #1277).

When invoking "Replace method call with property expression" quick fix (Ctrl+Shift+,) the call is replaced by "x" which resolves to the map delegate. A qualifier is required to maintain the reference to the method declared by C.