code: @Api
  	public HandlerRegistration addFeatureTransactionHandler(final FeatureTransactionHandler handler) {
  		return handlerManager.addHandler(FeatureTransactionHandler.TYPE, handler);
  	}
docs: Add a new handler for {@link FeatureTransactionEvent}s.
  
  @param handler
  the handler to be registered
  @return handler registration
  @since 1.7.0