public void verify() {
    logger.info("Verifying properties");
    Enumeration keys = props.propertyNames();
    while (keys.hasMoreElements()) {
      Object key = keys.nextElement();
      if (!referenceSet.contains(key)) {
        logger.warn("Property {} is not valid", key);
      } else {
        logger.info("Property {} is overridden to {}", key, props.getProperty(key.toString()));
      }
    }
  }
Get a string property or throw and exception if no such property is defined.
ambry-api/src/main/java/com/github/ambry/config/VerifiableProperties.java