code: public static void notEmpty(String value, Supplier<String> message) {
      if (isEmpty(value)) {
        throw new IllegalArgumentException(message.get());
      }
    }
docs: Asserts that the given {@link String} is not empty.
  
  The assertion holds if and only if the {@link String String} is not the {@link String#isEmpty() empty String}.
  
  @param value {@link String} to evaluate.
  @param message {@link Supplier} containing the message used in the {@link IllegalArgumentException} thrown
  if the assertion fails.
  @throws java.lang.IllegalArgumentException if the {@link String} is empty.
  @see java.lang.String