code: public void singleStepTransfer(
              String connId,
              String destination,
              String location,
              KeyValueCollection userData,
              KeyValueCollection reasons,
              KeyValueCollection extensions
      ) throws WorkspaceApiException {
          try {
              VoicecallsidsinglesteptransferData transferData =
                      new VoicecallsidsinglesteptransferData();
              transferData.setDestination(destination);
              transferData.setLocation(location);
              transferData.setUserData(Util.toKVList(userData));
              transferData.setReasons(Util.toKVList(reasons));
              transferData.setExtensions(Util.toKVList(extensions));
              SingleStepTransferData data = new SingleStepTransferData();
              data.data(transferData);
  
              ApiSuccessResponse response = this.voiceApi.singleStepTransfer(connId, data);
              throwIfNotOk("singleStepTransfer", response);
          } catch (ApiException e) {
              throw new WorkspaceApiException("singleStepTransfer failed", e);
          }
      }
docs: Perform a single-step transfer to the specified destination.
  @param connId The connection ID of the call to transfer.
  @param destination The number where the call should be transferred.
  @param location Name of the remote location in the form of <SwitchName> or <T-ServerApplicationName>@<SwitchName>. This value is used by Workspace to set the location attribute for the corresponding T-Server requests. (optional)
  @param userData Key/value data to include with the call. (optional)
  @param reasons Information on causes for, and results of, actions taken by the user of the current DN. For details about reasons, refer to the [*Genesys Events and Models Reference Manual*](https://docs.genesys.com/Documentation/System/Current/GenEM/Reasons). (optional)
  @param extensions Media device/hardware reason codes and similar information. For details about extensions, refer to the [*Genesys Events and Models Reference Manual*](https://docs.genesys.com/Documentation/System/Current/GenEM/Extensions). (optional)