code: public B error(String errorCode) {
      ErrorEventDefinition errorEventDefinition = createErrorEventDefinition(errorCode);
      element.getEventDefinitions().add(errorEventDefinition);
  
      return myself;
    }
docs: Sets an error definition for the given error code. If already an error
  with this code exists it will be used, otherwise a new error is created.
  
  @param errorCode the code of the error
  @return the builder object