private Object createInstance(String className) throws Exception {
    try {
      Class<?> clazz = Class.forName(className);
      Constructor<?> ctor = clazz.getConstructor();
      return ctor.newInstance();
    } catch (ClassNotFoundException | NoSuchMethodException
            | IllegalAccessException | InstantiationException | InvocationTargetException e) {
      throw new ExecutorException(e);
    }
  }
retrieves the list of {@link CommandHandler}s setup in this environment
@return List of {@link CommandHandler}
samza-sql-shell/src/main/java/org/apache/samza/sql/client/cli/CliEnvironment.java