code: public void sendDTMF(
              String connId,
              String digits,
              KeyValueCollection reasons,
              KeyValueCollection extensions
      ) throws WorkspaceApiException {
          try {
              VoicecallsidsenddtmfData dtmfData = new VoicecallsidsenddtmfData();
              dtmfData.setDtmfDigits(digits);
              dtmfData.setReasons(Util.toKVList(reasons));
              dtmfData.setExtensions(Util.toKVList(extensions));
              SendDTMFData data = new SendDTMFData();
              data.data(dtmfData);
  
              ApiSuccessResponse response = this.voiceApi.sendDTMF(connId, data);
              throwIfNotOk("sendDTMF", response);
          } catch (ApiException e) {
              throw new WorkspaceApiException("sendDTMF failed", e);
          }
      }
docs: Send DTMF digits to the specified call. You can send DTMF digits individually with multiple requests or together with multiple digits in one request.
  @param connId The connection ID of the call.
  @param digits The DTMF digits to send to the call.
  @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)