### Question:
EtcdConfigSourceBuilder extends AbstractConfigSourceBuilder<EtcdConfigSourceBuilder, EtcdEndpoint> implements PollableSource.Builder<EtcdConfigSourceBuilder>,
                   WatchableSource.Builder<EtcdConfigSourceBuilder, EtcdEndpoint>,
                   ParsableSource.Builder<EtcdConfigSourceBuilder>,
                   Builder<EtcdConfigSource> { @Override public EtcdConfigSourceBuilder pollingStrategy(PollingStrategy pollingStrategy) { return super.pollingStrategy(pollingStrategy); } EtcdConfigSourceBuilder(); @Override EtcdConfigSource build(); @Override EtcdConfigSourceBuilder config(Config metaConfig); @Override EtcdConfigSourceBuilder parser(ConfigParser parser); @Override EtcdConfigSourceBuilder mediaType(String mediaType); @Override EtcdConfigSourceBuilder pollingStrategy(PollingStrategy pollingStrategy); @Override EtcdConfigSourceBuilder changeWatcher(ChangeWatcher<EtcdEndpoint> changeWatcher); EtcdConfigSourceBuilder uri(URI uri); EtcdConfigSourceBuilder key(String key); EtcdConfigSourceBuilder api(EtcdApi version); static final EtcdApi DEFAULT_VERSION; static final URI DEFAULT_URI; }### Answer:
@Test public void testPollingStrategy() { URI uri = URI.create("http: EtcdConfigSourceBuilder builder = EtcdConfigSource.builder() .uri(uri) .key("/registry") .api(EtcdApi.v2) .pollingStrategy(new TestingEtcdEndpointPollingStrategy()); }