private boolean validateTransactionConflictsAndMarkState(
        Operation request, ServiceDocument currentState) {
      if (currentState == null) {
        return false;
      }

      String requestTransactionId = request.getTransactionId();
      String currentStateTransactionId = currentState.documentTransactionId;

      if (request.getAction() == Action.GET) {
        if (requestTransactionId == null) {
          // non-transactional read
          if (currentStateTransactionId == null) {
            return false;
          } else {
            logTransactionConflict(request, currentState);
            return true;
          }
        } else {
          // transactional read
          if (currentStateTransactionId == null) {
            logTransactionUpdate(buildLogTransactionUpdateMsg(request, currentState));
            currentState.documentTransactionId = requestTransactionId;
            return false;
          } else {
            if (requestTransactionId.equals(currentStateTransactionId)) {
              return false;
            } else {
              logTransactionConflict(request, currentState);
              return true;
            }
          }
        }
      } else {
        if (requestTransactionId == null) {
          // non-transactional write
          if (currentStateTransactionId == null
              || request.hasPragmaDirective(PRAGMA_DIRECTIVE_DELETE_ON_TRANSACTION_END)) {
            return false;
          } else {
            logTransactionConflict(request, currentState);
            return true;
          }
        } else {
          // transactional write
          if (currentStateTransactionId == null) {
            logTransactionUpdate(buildLogTransactionUpdateMsg(request, currentState));
            currentState.documentTransactionId = requestTransactionId;
            return false;
          } else {
            if (requestTransactionId.equals(currentStateTransactionId)) {
              return false;
            } else {
              logTransactionConflict(request, currentState);
              return true;
            }
          }
        }
      }
    }
    private void handleClearTransaction(
        Operation request,
        ServiceDocument currentState,
        ClearTransactionRequest clearTransactionRequest) {
      if (currentState == null) {
        request.complete();
        return;
      }

      if (!request.getTransactionId().equals(currentState.documentTransactionId)) {
        if (clearTransactionRequest.transactionOutcome == TransactionOutcome.COMMIT) {
          String warning =
              String.format(
                  "Request to clear transaction %s from service %s but current transaction is: %s",
                  request.getTransactionId(),
                  this.service.getSelfLink(),
                  currentState.documentTransactionId);
          this.service.getHost().log(Level.WARNING, warning);
        }
        request.complete();
        return;
      }

      if (clearTransactionRequest.transactionOutcome == TransactionOutcome.ABORT
          && clearTransactionRequest.isUpdated) {
        // restore previous state
        URI previousStateQueryUri =
            UriUtils.buildDocumentQueryUri(
                this.service.getHost(),
                this.service.getSelfLink(),
                false,
                false,
                ServiceOption.PERSISTENCE);
        previousStateQueryUri =
            UriUtils.appendQueryParam(
                previousStateQueryUri,
                ServiceDocument.FIELD_NAME_VERSION,
                Long.toString(clearTransactionRequest.originalVersion));
        Operation previousStateGet =
            Operation.createGet(previousStateQueryUri)
                .setCompletion(
                    (o, e) -> {
                      if (e != null) {
                        request.fail(e);
                        return;
                      }
                      ServiceDocument previousState = o.getBody(currentState.getClass());
                      this.service
                          .getHost()
                          .log(
                              Level.INFO,
                              "Aborting transaction %s on service %s, current version %d, restoring version %d",
                              request.getTransactionId(),
                              this.service.getSelfLink(),
                              currentState.documentVersion,
                              clearTransactionRequest.originalVersion);
                      previousState.documentTransactionId = null;
                      this.service.setState(request, previousState);
                      request.complete();
                    });
        this.service.sendRequest(previousStateGet);
        return;
      }

      currentState.documentTransactionId = null;
      request.complete();
    }