code: public static void checkArgument(boolean test, @Nullable String message) {
      if (!test) {
        throw new IllegalArgumentException(message == null || message.isEmpty() ? IAE_DEFAULT_MSG : message);
      }
    }
docs: Throws a {@link IllegalArgumentException} with the specified message if the specified boolean
  value is false.
  <p>
  A default message will be used if the specified message is {@code null} or empty.
  </p>
  
  @param test    a boolean value
  @param message a {@link String} or {@code null}