code: public void loadRewards(BranchReferralStateChangedListener callback) {
          ServerRequest req = new ServerRequestGetRewards(context_, callback);
          if (!req.constructError_ && !req.handleErrors(context_)) {
              handleNewRequest(req);
          }
      }
docs: <p>Retrieves rewards for the current session, with a callback to perform a predefined
  action following successful report of state change. You'll then need to call getCredits
  in the callback to update the credit totals in your UX.</p>
  
  @param callback A {@link BranchReferralStateChangedListener} callback instance that will
  trigger actions defined therein upon a referral state change.