code: public ErrorEventDefinitionBuilder errorEventDefinition() {
      ErrorEventDefinition errorEventDefinition = createEmptyErrorEventDefinition();
      element.getEventDefinitions().add(errorEventDefinition);
      return new ErrorEventDefinitionBuilder(modelInstance, errorEventDefinition);
    }
docs: Creates an error event definition
  and returns a builder for the error event definition.
  
  @return the error event definition builder object