@Override
        public void cancel() {
            if (cancelledUpdater.compareAndSet(this, 0, 1)) {
                super.cancel();
                final CancelledSubscriptionException cause = CancelledSubscriptionException.get();
                if (containsNotifyCancellation(options)) {
                    downstream.onError(cause);
                }
                downstream = NoopSubscriber.get();
                abortUnsubscribedSources(cause);
            }
        }
Relay items in order from subsequent {@link StreamMessage}s as a single {@link StreamMessage} source.
core/src/main/java/com/linecorp/armeria/common/stream/ConcatArrayStreamMessage.java