code: private static void checkClassesValid(List<Class<?>> classList) throws InvalidClassException {
          // check classes is valid for generating DataSerializer, if not - throw NotSerializableException with detailed
          // reason
          for (Class<?> clazz : classList) {
              Introspector.checkClassIsSerialized(clazz);
          }
  
          // check classes do not contain duplicated @AutoSerializable.dataSerializerID
          checkDataSerializerIDIsUnique(classList);
      }
docs: ------------------------ PRIVATE