If you have a package, say, erm, myjavaprogram, and it works with the Sun JVM, IBM JVM, Blackdown and kaffe, but not sablevm, then my interpretation is that the dependencies should look like this:
java2-runtime | kaffe and that kaffe and sablevm, because they don't support everything that is in Java 2, should not Provide java2-runtime. Is this unreasonable?