All inheritable declaration annotations are being inherited, regardless of their relationship

When inheriting related declaration annotations, the element should inherit 
only the "stronger ones", instead of all of them.

For example:
class Super {
     @Pure 
     void foo(){}
}   

class clazz extends Super {
     @SideEffectFree
     @Override
     void foo(){}
}

We want clazz.foo() to have only the @Pure annotation since @Pure and 
@SideEffectFree are related, but instead it currently has both of them.

There is a test case for that issue in 
checker-framework/checker/jtreg/nullness/inheritDeclAnnoPersist/Extends.java: 
method m3().

Original issue reported on code.google.com by pbsf...@gmail.com on 17 Jul 2014 at 10:12

Start with checker/jtreg/nullness/inheritDeclAnnoPersist/Extends.java, especially method m3(), and run the relevant jtreg test to reproduce the annotation inheritance behavior. Trace the declaration-annotation inheritance logic that handles related annotations. Done means only the stronger related annotation, such as @Pure rather than both @Pure and @SideEffectFree, is inherited.