code: public void presentPaymentMethodSelection() {
          final Intent paymentMethodsIntent = mPaymentMethodsActivityStarter.newIntent()
                  .putExtra(EXTRA_PAYMENT_SESSION_ACTIVE, true);
          mHostActivity.startActivityForResult(paymentMethodsIntent, PAYMENT_METHOD_REQUEST);
      }
docs: Launch the {@link PaymentMethodsActivity} to allow the user to select a payment method,
  or to add a new one.