Fixed an error message about required property

[superstas]

Hi there!

I've fixed an error message about required property. 1) There is a data structure:

message Person {
     required uint32 person_id = 1;
}

2) Example of using:

<?php

require "autoload.php";

$person = new \Person();
var_dump($person->serializeToString());

There was error: "the class does not have required property person_id" , but he does.