(Java) Covariance in generic types of parameters?

[James Ide <id...@berkeley.edu>]

Hello,

I'm beginning a new project using Avro and have just gotten to the
code-generation phase. I've noticed that a little message declaration like:
  map<string> test(map<string> arg);
is translated into:
  Map<CharSequence, CharSequence> test(Map<CharSequence, CharSequence> arg);

Is there a way to generate code that uses covariant parameter types (and
contravariant return types FWIW)? For example, something like:
  Map<? super CharSequence, ? super CharSequence> test(Map<? extends
CharSequence, ? extends CharSequence> arg);

Alternatively, is there a way to eliminate lengthy type declarations like
Map<CharSequence, CharSequence> from my code that calls into Avro IPC
methods? Even Map<Utf8, Utf8> looks pretty attractive.

Thanks,
James