### Question:
FileConfigSource extends AbstractConfigSource implements WatchableSource<Path>, ParsableSource, PollableSource<byte[]> { public static Builder builder() { return new Builder(); } FileConfigSource(Builder builder); static FileConfigSource create(Config metaConfig); static Builder builder(); @Override boolean isModified(byte[] stamp); @Override Path target(); @Override Optional<ConfigParser.Content> load(); @Override Optional<ConfigParser> parser(); @Override Optional<String> mediaType(); @Override Optional<PollingStrategy> pollingStrategy(); @Override Optional<ChangeWatcher<Object>> changeWatcher(); @Override boolean exists();  }### Answer:
@Test public void testBuilder() { ConfigSource configSource = ConfigSources.file("application.conf").build(); assertThat(configSource, notNullValue()); }