code: public static URL readAppConfig(Properties properties, String confFile) {
          Enumeration<URL> urls = IOUtils.getResources(confFile);
          URL url = null;
          if (urls.hasMoreElements()) {
              InputStream in = null;
              Set<URL> urlSet = Sets.newHashSet(Iterators.forEnumeration(urls));
  
              if (urlSet.size() > 1) {
                  String errorMsg = Messages.get("info.load.config.multi.error",
                          StringUtils.join(urlSet.stream().map(Application::toExternalForm), LINE_SEPARATOR));
                  logger.error(errorMsg);
                  throw new ConfigErrorException(errorMsg);
              }
  
              url = urlSet.iterator().next();
  
              try {
                  logger.trace(Messages.get("info.load", toExternalForm(url)));
                  in = url.openStream();
              } catch (IOException e) {
                  logger.error(Messages.get("info.load.error", toExternalForm(url)));
              }
              loadProperties(in, properties, url);
          } else {
              logger.warn(Messages.get("info.load.error.not.found", confFile));
          }
          return url;
      }
docs: <p>readAppConfig.</p>
  
  @param properties a {@link java.util.Properties} object.
  @param confFile   a {@link java.lang.String} object.
  @return a {@link java.net.URL} object.