private void respondWithErrorIfNotResponded() {
            if ( tryHasResponded() ) return;
            ResponseDispatch.newInstance(Response.Status.INTERNAL_SERVER_ERROR).dispatch(responseHandler);
            log.warning("This handler is not async but did not produce a response. Responding with status 500." +
                        "(If this handler is async, pass a boolean true in the super constructor to avoid this.)");
        }
Invoked to write an error response when the worker pool is overloaded.
A subclass may override this method to define a custom response.
container-core/src/main/java/com/yahoo/container/jdisc/ThreadedRequestHandler.java