Improve/re-implement a parser of generic signatures in DRLVM kernel classes , and move this functionality to classlib (luni ?), so other VMs could reuse it for 1.5 support. The current impl is somewhat messy and half-baked, one need to invent more shaped and modular API to the parser. One more possible issue is parser's dependency on antlr, which may be considered overkill for this duty. I think antlr has its pros, like more illustrative code with clear correlation to formal grammar ; unfortunately this is not the case with the impl in question. OTOH minimizing number of dependencies for VM is always good.
 http://java.sun.com/docs/books/vmspec/2nd-edition/ClassFileFormat-Java5.pdf Para 4.4.4