docs: void terminateRequest() {
          int oldVal = state;
          if (allAreSet(oldVal, FLAG_REQUEST_TERMINATED)) {
              // idempotent
              return;
          }
          if (requestChannel != null) {
              requestChannel.requestDone();
          }
          this.state = oldVal | FLAG_REQUEST_TERMINATED;
          if (anyAreSet(oldVal, FLAG_RESPONSE_TERMINATED)) {
              invokeExchangeCompleteListeners();
          }
      }