As part of the non-core API generification in Tiger (4964490), the class java.io.ObjectStreamField as generified as Comparable<Object> rather than Comparable<ObjectStreamField>.  However, the class actually is only comparable against itself so it should be Comparable<ObjectStreamField>.  Making this change now would be binary compatable since there is no bridge method generated for Comparable<Object>.  However, there would be a source incompatability, but that is essentially the same source incompatabilty of catching runtime exceptions at compile time that generics is intended to introduce.