title: Gson - questions about versioning
body: <p>I am looking at the <a href="https://sites.google.com/site/gson/gson-user-guide#TOC-Versioning-Support" rel="nofollow">Versioning Support section</a> of the Gson User Guide.</p>
  
  <p>Question 1: It says you can use the @Since annotation on Classes, Fields, and (in a future release) Methods.  I understand serialization of an object's fields, but what does it mean to serialize a <em>class</em> and a <em>method</em>?</p>
  
  <p>Question 2: It says that when you create your Gson object, you can specify a version, and then any field annotated with @Since and a version number greater than that will be ignored.  What exactly is the point of this?  I know that when the Json contains extra fields that do not exist in the Java class to which it is being deserialized, then those fields are ignored.  So why would you ever need to use the @Since annotation?</p>