code: public boolean overrideEquivalent(Type t, Type s) {
          return hasSameArgs(t, s) ||
              hasSameArgs(t, erasure(s)) || hasSameArgs(erasure(t), s);
      }
docs: Returns true iff these signatures are related by <em>override
  equivalence</em>.  This is the natural extension of
  isSubSignature to an equivalence relation.
  
  @jls section 8.4.2.
  @see #isSubSignature(Type t, Type s)
  @param t a signature (possible raw, could be subjected to
  erasure).
  @param s a signature (possible raw, could be subjected to
  erasure).
  @return true if either argument is a sub signature of the other.