The jaxp repository has a build.xml and nbproject/project.xml which allows it to be opened in NetBeans as a free form project.
However, the source folder definition is missing - and there's no javadoc target to generate a javadoc preview of the jaxp packages either.
It would be very useful to be able to use NetBeans to edit the jaxp sources and to generate a preview of the associated javadoc.