presto-hive/src/main/java/io/prestosql/plugin/hive/gcs/GoogleGcsConfigurationInitializer.java/GoogleGcsConfigurationInitializer/initializeConfiguration
class GoogleGcsConfigurationInitializer:    @Override
    public void initializeConfiguration(Configuration config)
    {
        config.set("fs.gs.impl", GoogleHadoopFileSystem.class.getName());

        if (useGcsAccessToken) {
            // use oauth token to authenticate with Google Cloud Storage
            config.set(AUTH_SERVICE_ACCOUNT_ENABLE.getKey(), "false");
            config.set(AUTHENTICATION_PREFIX + ACCESS_TOKEN_PROVIDER_IMPL_SUFFIX, GcsAccessTokenProvider.class.getName());
        }
        else if (jsonKeyFilePath != null) {
            // use service account key file
            config.set(AUTH_SERVICE_ACCOUNT_ENABLE.getKey(), "true");
            config.set(AUTHENTICATION_PREFIX + JSON_KEYFILE_SUFFIX, jsonKeyFilePath);
        }
    }