code: public ApiSuccessResponse initiateConference(String id, InitiateConferenceData initiateConferenceData) throws ApiException {
          ApiResponse<ApiSuccessResponse> resp = initiateConferenceWithHttpInfo(id, initiateConferenceData);
          return resp.getData();
      }
docs: Initiate a conference
  Initiate a two-step conference to the specified destination. This places the existing call on hold and creates a new call in the dialing state (step 1). After initiating the conference you can use [/voice/calls/{id}/complete-conference](/reference/workspace/Voice/index.html#completeConference) to complete the conference and bring all parties into the same call (step 2).
  @param id The connection ID of the call to start the conference from. This call will be placed on hold. (required)
  @param initiateConferenceData  (required)
  @return ApiSuccessResponse
  @throws ApiException If fail to call the API, e.g. server error or cannot deserialize the response body