case ExchangePolicyEnum::kKeyRange: {
                size_t target = getTargetConsumer(input.getDocument());
                bool full = _consumers[target]->appendDocument(std::move(input), _maxBufferSize);
                if (full && _orderPreserving) {
                    // TODO send the high watermark here.
                }
                if (full)
                    return target;
            } break;