code: public static <T> T assertNull(@Nullable final String failMessage, @Nullable final T object) {
      if (object != null) {
        final String txt = failMessage == null ? "Object must be NULL" : failMessage;
        final AssertionError error = new AssertionError(txt);
        MetaErrorListeners.fireError(txt, error);
        throw error;
      }
      return object;
    }
docs: Assert that value is null
  
  @param <T>         type of the object to check
  @param failMessage the message to be provided for failure, can be null
  @param object      the object to check
  @return the same input parameter if all is ok
  @throws AssertionError it will be thrown if the value is not null
  @since 1.1.0