code: public boolean isSubclassOf(TypeElement t1, TypeElement t2) {
          return typeUtils.isSubtype(t1.asType(), t2.asType());
      }
docs: Test whether a class is a subclass of another class.
  
  @param t1 the candidate superclass.
  @param t2 the target
  @return true if t1 is a superclass of t2.