code: public Object eval(String script) {
  //        // use Java's ScriptEngine at the moment
  //        ScriptEngineManager manager = new ScriptEngineManager();
  //        ScriptEngine jsEngine = manager.getEngineByName("JavaScript");
  //        try {
  //            return jsEngine.eval(script);
  //        } catch (ScriptException e) {
  //            throw new RuntimeException(e);
  //        }
          return eval(script, Collections.<String, Object>emptyMap());
      }
docs: Evaluate a script and return executing result. Note the API is not mature yet
  don't use it in your application
  
  @param script
  @return the result