code: public static void init() {
  
          // Get configuration
  
          // Read from "server.properties" or custom file.
          String configFile = null;
          Properties serverProperties = new Properties();
          try {
              configFile = System.getProperty(PROPERTY_PREFIX + "config", "server.properties");
              LOG.info("Loading server configuration from " + configFile);
  
              try (InputStream is = new FileInputStream(configFile)) {
                  serverProperties.load(is);
              }
  
          } catch (FileNotFoundException e) {
              LOG.warn(configFile + " not found.");
          } catch (IOException e) {
              LOG.error("Unexpected error reading " + configFile);
          }
  
          init(serverProperties);
      }
docs: Read server configuration from System properties and from server.properties.