code: public ApiResponse<ApiSuccessResponse> singleStepConferenceWithHttpInfo(String id, SingleStepConferenceData singleStepConferenceData) throws ApiException {
          com.squareup.okhttp.Call call = singleStepConferenceValidateBeforeCall(id, singleStepConferenceData, null, null);
          Type localVarReturnType = new TypeToken<ApiSuccessResponse>(){}.getType();
          return apiClient.execute(call, localVarReturnType);
      }
docs: Create a conference in a single step
  Perform a single-step conference to the specified destination. This adds the destination to the existing call, creating a conference if necessary.
  @param id The connection ID of the call to conference. (required)
  @param singleStepConferenceData  (required)
  @return ApiResponse&lt;ApiSuccessResponse&gt;
  @throws ApiException If fail to call the API, e.g. server error or cannot deserialize the response body