Sounds like one of the JTS classes that is generated from idl at build time. Poke around in the bulid tree after running 'ant jts', it will be there someplace unless the build cleans it up.
Yep. Exactly as you described ... the .java sources are apparently born at build-time from IDL and then killed off immediately, explicitly, by the build. Sort of the .java version of sudden infant death syndrome ...
I'm in the process of prototyping a new build system that's a bit cleaner, particularly with regard to dependency management. Along the way I'm taking into account an outstanding request to provide a source jar with each release, largely for mvn/eclipse environments. In the meanwhile you should be able to disable the bit that removes the generated files without much harm.