code: public Config loadConfig(final @Nullable String confname, final String rootPath) {
  		// load configuration properties
  		Config config;
  		final String confname2 = trimToNull(confname);
  		if (confname2 != null) {
  			final ConfigParseOptions options = ConfigParseOptions.defaults().setAllowMissing(false);
  			final Config customConfig = ConfigFactory.parseFileAnySyntax(new File(confname2), options);
  			final Config regularConfig = ConfigFactory.load();
  			final Config combined = customConfig.withFallback(regularConfig);
  			config = ConfigFactory.load(combined);
  		} else {
  			config = ConfigFactory.load();
  		}
  		// validate
  		config.checkValid(ConfigFactory.defaultReference(), rootPath);
  		return config;
  	}
docs: Loads and merges application configuration with default properties.
  @param confname - optional configuration filename
  @param rootPath - only load configuration properties underneath this path that this code
  module owns and understands
  @return Configuration loaded from the provided filename or from default properties.