[Checkers] AnnotatedTypeMirror type parameter cache

[Mahmood Ali]

Greetings,

Thank you for reporting this bug.  I appreciate all your bug reports  
that help us make our system more correct and robust.

I will work on fixing in the near future.  Removing the type parameter  
cache has been in my TODO agenda for quite a bit now.

Also, IGJ and the framework as a whole does not honor annotations on  
type variables/parameters.  Actually their behavior for now in these  
cases is unspecified.  Hence you getting these unpredicted errors when  
you add annotations to T in
>     public void test(@Mutable T test, @Immutable T test2)

There are a couple of issues that need to be resolved before we can  
fully specify the proper behavior.

Regards,
Mahmood