/** Indicates no response processor is available. */
    NO_RESPONSE_PROCESSOR,
    /** Indicates no rule is available for processing. */
    NO_RULE,
    /** Indicates a system error occurred. */
    SYSTEM_ERROR

    }

    @Override
    public OptionalThing<ApiResponse> handleServerException(final ApiFailureResource resource, final Throwable cause) {
        return OptionalThing.of(asJson(createFailureBean(Status.SYSTEM_ERROR, createMessage(resource, cause))));
    }

    // ===================================================================================
    //                                                                        Assist Logic

            break;
        case NO_RESPONSE_PROCESSOR:
            processNoResponseProcessor(objs);
            break;
        case NO_RULE:
            processNoRule(objs);
            break;
        case SYSTEM_ERROR:
            processSystemError(objs);
            break;
        default:
            processDefault(objs);
            break;
        }
    }

    /**

                    crawlerContext.intervalController.delay(IntervalController.WAIT_NEW_URL);
                }
            }
        } catch (final Throwable t) {
            log(logHelper, LogType.SYSTEM_ERROR, t);
        } finally {
            // remove crawlerContext from thread
            CrawlingParameterUtil.setCrawlerContext(null);
            CrawlingParameterUtil.setUrlQueueService(null);

        /** Successful response status. */
        OK(0),
        /** Bad request status indicating client error. */
        BAD_REQUEST(1),
        /** System error status indicating server error. */
        SYSTEM_ERROR(2),
        /** Unauthorized status indicating authentication failure. */
        UNAUTHORIZED(3),
        /** General failure status. */
        FAILED(9);

        private final int id;