docs: public void completePayment(@NonNull PaymentCompletionProvider provider) {
          provider.completePayment(mPaymentSessionData,
                  new PaymentResultListener() {
                      @Override
                      public void onPaymentResult(@NonNull @PaymentResult String paymentResult) {
                          mPaymentSessionData.setPaymentResult(paymentResult);
                          mCustomerSession.resetUsageTokens();
                          if (mPaymentSessionListener != null) {
                              mPaymentSessionListener
                                      .onPaymentSessionDataChanged(mPaymentSessionData);
                          }
                      }
                  });
      }