While they are java keywords as we know them this is not a complete jdk, so many (almost single good one) libraries dont work. I remember spending a week trying to port itext pdf generation lib to gae. While it worked we got concerned by the legal issues of us riping code out of sun/ibm/harmony jdks to add missing jdk classes.

Java here is a pure marketing effort to convince a clueless manager saying hey we got java!