Merge configuration using MergeConfigurationSource

Cfg4jConfigurationMerge.java

@Bean
ConfigurationProvider configurationProvider(ConfigurationSource configurationSource,
                                           @Value("${configuration.environment}") String configurationEnvironment) {

 ConfigurationSource localOverrideSource = new FilesConfigurationSource(() -> Collections.singletonList(Paths.get("application.properties")));
 MergeConfigurationSource mergeConfigurationSource = new MergeConfigurationSource(localOverrideSource, configurationSource);

 return new ConfigurationProviderBuilder()
     .withConfigurationSource(mergeConfigurationSource)
     .withEnvironment(new ImmutableEnvironment("app/" + configurationEnvironment + "/feature"))
     .withReloadStrategy(new PeriodicalReloadStrategy(30, TimeUnit.SECONDS))
     .build();
}