Braintree/src/main/java/com/braintreepayments/api/BraintreeFragment.java
public void getGoogleApiClient(final BraintreeResponseListener<GoogleApiClient> listener) {
        waitForConfiguration(new ConfigurationListener() {
            @Override
            public void onConfigurationFetched(Configuration configuration) {
                GoogleApiClient googleApiClient = getGoogleApiClient();
                if (googleApiClient != null) {
                    listener.onResponse(googleApiClient);
                }
            }
        });
    }
public void getGoogleApiClient(final BraintreeResponseListener<GoogleApiClient> listener) {
        waitForConfiguration(new ConfigurationListener() {
            @Override
            public void onConfigurationFetched(Configuration configuration) {
                GoogleApiClient googleApiClient = getGoogleApiClient();
                if (googleApiClient != null) {
                    listener.onResponse(googleApiClient);
                }
            }
        });
    }
Obtain an instance of a {@link GoogleApiClient} that is connected or connecting to be used
for Android Pay. This instance will be automatically disconnected in
{@link BraintreeFragment#onStop()} and automatically connected in
{@link BraintreeFragment#onResume()}.
<p/>
Connection failed and connection suspended errors will be sent to
{@link BraintreeErrorListener#onError(Exception)}.

@param listener {@link BraintreeResponseListener<GoogleApiClient>} to receive the
{@link GoogleApiClient} in
{@link BraintreeResponseListener<GoogleApiClient>#onResponse(GoogleApiClient)}.