Why are wrapper classes not suited for use in callback frameworks?

Question

I just read the question what are callback frameworks?, where the asker cites the following from Effective Java:

The disadvantages of wrapper classes are few. One caveat is that wrapper classes are not suited for use in callback frameworks, wherein objects pass selfreferences to other objects for subsequent invocations (“callbacks”).

So I am curious, why are wrapper classes not suited for use in callback frameworks? And can you provide an example of what the problem is?