ConfigObserver { public <T> ConfigObserver onPrefixedValue(String prefix, ConfigValueListener<Map<String, String>> listener) { return onConfigChange(new ConfigListener() { @Override public void onConfigChanged(Set<String> changedKeys, ConfigMap newConfiguration) { if (changeIncludes(changedKeys, prefix)) { applyConfiguration(listener, newConfiguration.subMap(prefix).orElse(new ConfigMap())); } } }); } ConfigObserver(String applicationName);  ConfigObserver(File configDirectory, String applicationName);  ConfigObserver(File configDirectory, String applicationName, List<String> profiles);  ConfigObserver(ConfigLoader configLoader); ConfigObserver onConfigChange(ConfigListener listener); ConfigObserver onSingleConfigValue(String key, Function<String, T> transformer, T defaultValue, ConfigValueListener<T> listener); ConfigObserver onStringValue(String key, String defaultValue, ConfigValueListener<String> listener); ConfigObserver onIntValue(String key, int defaultValue, ConfigValueListener<Integer> listener); ConfigObserver onLongValue(String key, long defaultValue, ConfigValueListener<Long> listener); ConfigObserver onInetSocketAddress(String key, int defaultPort, ConfigValueListener<InetSocketAddress> listener); ConfigObserver onInetSocketAddress(String key, InetSocketAddress defaultAddress, ConfigValueListener<InetSocketAddress> listener); ConfigObserver onDurationValue(String key, Duration defaultValue, ConfigValueListener<Duration> listener); ConfigObserver onStringListValue(String key, String defaultValue, ConfigValueListener<List<String>> listener); ConfigObserver onPrefixedValue(String prefix, ConfigValueListener<Map<String, String>> listener); ConfigObserver onPrefixedValue(String prefix, ConfigListener.Transformer<T> transformer, ConfigValueListener<T> listener); ConfigObserver onPrefixedOptionalValue(String prefix, ConfigListener.Transformer<T> transformer, ConfigValueListener<Optional<T>> listener); ConfigObserver onPrefixedOptionalValue(String prefix, ConfigValueListener<Optional<Map<String, String>>> listener); void updateConfiguration(Map<String, String> newConfiguration);  }
@Test public void shouldValidateRequiredValue() { AtomicReference<Credentials> credentials = new AtomicReference<>(); expectedLogEvents.expectPattern(ConfigObserver.class, Level.ERROR, "Failed to notify listener while reloading {}"); observer.onPrefixedValue("credentials", Credentials::new, credentials::set); }