docs: private String stringId() throws RecognitionException {
          if ( input.LA( 1 ) == DRL5Lexer.ID ) {
              Token id = match( input,
                                DRL5Lexer.ID,
                                null,
                                null,
                                DroolsEditorType.IDENTIFIER );
              if ( state.failed ) return null;
              return id.getText();
          } else if ( input.LA( 1 ) == DRL5Lexer.STRING ) {
              Token id = match( input,
                                DRL5Lexer.STRING,
                                null,
                                null,
                                DroolsEditorType.IDENTIFIER );
              if ( state.failed ) return null;
              return StringUtils.unescapeJava( safeStripStringDelimiters( id.getText() ) );
          } else {
              throw new MismatchedTokenException( DRL5Lexer.ID,
                                                  input );
          }
      }