code: public static void isNull(@Nullable final Object object, final String message) {
      if (object != null) {
        throw new IllegalArgumentException(message);
      }
    }
docs: Assert that an object is {@code null}.
  
  <pre class="code">
  Assert.isNull(value, "The value must be null");
  </pre>
  
  @param object the object to check
  @param message the exception message to use if the assertion fails
  @throws IllegalArgumentException if the object is not {@code null}