code: public static void assertNull(String message, Object object) {
          if (object == null) {
              return;
          }
          failNotNull(message, object);
      }
docs: Asserts that an object is null. If it is not, an {@link AssertionError}
  is thrown with the given message.
  
  @param message the identifying message for the {@link AssertionError} (<code>null</code>
  okay)
  @param object Object to check or <code>null</code>