docs: private void nestedConstraint( PatternDescrBuilder< ? > pattern, String prefix ) throws RecognitionException {
          int prefixLenght = getNestedConstraintPrefixLenght();
  
          int prefixStart = input.index();
          prefix += input.toString( prefixStart, prefixStart + prefixLenght - 2 );
          for (int i = 0; i < prefixLenght; i++) {
              input.consume();
          }
  
          constraints( pattern, prefix );
          match( input,
                  DRL5Lexer.RIGHT_PAREN,
                  null,
                  null,
                  DroolsEditorType.SYMBOL );
      }