docs: public static KickflipApiClient getApiClient(Context context, KickflipCallback callback) {
          checkNotNull(sClientKey);
          checkNotNull(sClientSecret);
          if (sKickflip == null || !sKickflip.getConfig().getClientId().equals(sClientKey)) {
              sKickflip = new KickflipApiClient(context, sClientKey, sClientSecret, callback);
          } else if (callback != null) {
              callback.onSuccess(sKickflip.getActiveUser());
          }
          return sKickflip;
      }