We need to look into this. You shouldn't need to use a snapshot of anything just to avoid this error.
The relevant part says, "For the AbstractMethodError, it looks like a bug in Xalan. The JTidy document is DOM level 1 and Xalan should know not to call getXmlStandalone, which is DOM level 3. However, you should be able to work around this error by replacing the JTidy jar with the latest snapshot available here:
This snapshot contains a default implementation for getXmlStandalone."