xml schema version always null

I'm using this http://ift.tt/1rWapfy, in my android project. I'm iterating through an XML schema which has a version such as the following,

<xs:schema version="4.0.2" xmlns:xs="http://ift.tt/tphNwY"
 attributeFormDefault="unqualified" elementFormDefault="qualified" >

But when version always returns null.

I went through the source, and it doesn't look like it's being set anywhere. Can someone tell me how to extract from 'version' from the XML document.