code: public final boolean makesStructs() {
      if (!hasInstanceType()) {
        return false;
      }
      if (propAccess == PropAccess.STRUCT) {
        return true;
      }
      FunctionType superc = getSuperClassConstructor();
      if (superc != null && superc.makesStructs()) {
        setStruct();
        return true;
      }
      return false;
    }
docs: When a class B inherits from A and A is annotated as a struct, then B automatically gets the
  annotation, even if B's constructor is not explicitly annotated.