Chapter 4: Ticket: Handling Errors, test Cases pass but not throwing exception

I have implemented the below code, but it is passing both the test cases. It is not throwing any Exception.

Can you please help me did I missed something or can you please give me some hint.

  private boolean validIdValue(String movieId) {
    //TODO> Ticket: Handling Errors - implement a way to catch a
    //any potential exceptions thrown while validating a movie id.
    //Check out this method's use in the method that follows.
	  try {
		  //ObjectId obj1 = new ObjectId();
	  catch(MongoWriteException e)
    return true;

Please let me know if I need to modify something or did I miss something?

Any help will be appreciated.