code: public static <T> void fire(final HasFormSubmitHandlers<T> source, final T value) {
      if (type != null) {
        final FormSubmitEvent<T> event = new FormSubmitEvent<>(value);
        source.fireEvent(event);
      }
    }
docs: Fires a form submit event on all registered handlers in the handler manager. If no such
  handlers exist, this method will do nothing.
  
  @param <T> the old value type
  @param source the source of the handlers
  @param value the value