docs: public QueryCommand parse( TypeSystem typeSystem,
                                 String language,
                                 String query ) {
          CheckArg.isNotNull(language, "language");
          CheckArg.isNotNull(typeSystem, "typeSystem");
          CheckArg.isNotNull(query, "query");
          QueryParser parser = parsers.get(language.trim().toLowerCase());
          if (parser == null) {
              throw new IllegalArgumentException(GraphI18n.unknownQueryLanguage.text(language));
          }
          return parser.parseQuery(query, typeSystem);
      }