Not sure how much this affects us but the following were posted to WTP-DEV mailing list:

"In an effort to become more compliant with the W3C DOM specification, we are planning to make changes that may require action on your behalf. The current behavior of the WTP implementation of org.w3c.dom.Element returns null for getAttribute(String) and getAttributeNS(String) if the attribute value is not specified. After the change, calls to these methods will return an empty string if the attribute value is not specified. This change is required to comply with the interface, and will correct various NullPointerExceptions when EMF is used with our DOM implementation and the EMF code is undeniably correct.

What is required?
If your code was depending on the DOM returning null to indicate a missing attribute, the code should be changed to hasAttribute(String) or hasAttributeNS(String) before obtaining the value.

When will this change be implemented?
During Milestone 3 of WTP 3.2.

Where can I find more information?
https://bugs.eclipse.org/bugs/show_bug.cgi?id=272378"

We had some code in th reveng.xml editing which I believe depended on this kind of behavior. Best to adjust to the spec so we work on both versions.