code: public void startRecording(String connId) throws WorkspaceApiException {
          try {
              ApiSuccessResponse response = this.voiceApi.startRecording(connId, null);
              throwIfNotOk("startRecording", response);
          } catch (ApiException e) {
              throw new WorkspaceApiException("startRecording failed.", e);
          }
      }
docs: Start recording the specified call. Recording stops when the call is completed or you send `stopRecording()`
  on either the call or the DN.
  @param connId The connection ID of the call.