@Override
        public void onCompleted() {
            try (TaskCloseable ignored = PerfMark.traceTask(filter, f -> f.filterName() + ".onCompletedAsync")) {
                PerfMark.linkIn(onCompletedLinkOut.get());
                decrementConcurrency();
                if (outMesg == null) {
                    outMesg = filter.getDefaultOutput(inMesg);
                }
                recordFilterCompletion(ExecutionStatus.SUCCESS, filter, startTime, inMesg, snapshot);
                resumeInBindingContext(outMesg, filter.filterName());
            } catch (Exception e) {
                handleException(inMesg, filter.filterName(), e);
            }
        }
This is typically set by a filter when wanting to reject a request and also reduce load on the server by
 not processing anymore filterChain
zuul-core/src/main/java/com/netflix/zuul/netty/filter/BaseZuulFilterRunner.java