public String getString(String name) {
    if (!containsKey(name)) {
      throw new IllegalArgumentException("Missing required property '" + name + "'");
    } else {
      return getProperty(name);
    }
  }
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