code: public CampaignService getCampaignService() {
          if (_campaignService == null) {
              synchronized (CCApi2.class) {
                  if (_campaignService == null) {
                      _campaignService = _retrofit.create(CampaignService.class);
                  }
              }
          }
  
          return _campaignService;
      }
docs: Gets the campaign service.
  
  @return the campaign service