code: protected Diff processRevision(final Revision revision)
  		throws UnsupportedEncodingException
  	{
  
  		Diff diff = super.processRevision(revision);
  		if (diff == null) {
  			this.ignoredRevisionsCounter++;
  		}
  		else {
  			this.revisionCounter++;
  			this.diffPartCounter += diff.size();
  		}
  
  		return diff;
  	}
docs: Calculates the diff for the given revision.
  
  @param revision
  Reference to a revision
  @return Diff
  
  @throws UnsupportedEncodingException
  if the character encoding is unsupported