docs: private Send handle(SelectionKey key, Receive request) {
          final short requestTypeId = request.buffer().getShort();
          final RequestKeys requestType = RequestKeys.valueOf(requestTypeId);
          if (requestLogger.isTraceEnabled()) {
              if (requestType == null) {
                  throw new InvalidRequestException("No mapping found for handler id " + requestTypeId);
              }
              String logFormat = "Handling %s request from %s";
              requestLogger.trace(format(logFormat, requestType, channelFor(key).socket().getRemoteSocketAddress()));
          }
          RequestHandler handlerMapping = requesthandlerFactory.mapping(requestType, request);
          if (handlerMapping == null) {
              throw new InvalidRequestException("No handler found for request");
          }
          long start = System.nanoTime();
          Send maybeSend = handlerMapping.handler(requestType, request);
          stats.recordRequest(requestType, System.nanoTime() - start);
          return maybeSend;
      }