xmlParserAPIs.jar contains the DOM level 2, SAX 2.0 and JAXP 1.1 API's, which used to be in xerces.jar (see the Xerces FAQ). Maybe there is another source for these classes but that is not obvious to me. Sun JDK 1.4.1_01 contains some of them but e.g. not org.w3c.dom.ranges.* I think the fix is simple: replace "dojar build/xerces*.jar" with "dojar build/x*.jar" in the ebuild. xmlParserAPIs.jar just doesn't get copied after being built.
Fixed now on portage tree. Its masked as testing. Thanks.