The Present Perfect (the other perfect tenses too) is a really confusing tense, on one hand there is not doubt that it belongs to the family of the present tenses,
on the other it often refers to the past.
That brings us to the question of how the sentence behaves when introduced by the Present Perfect in the reported speech:
Do you know what the answer is? The answer is: won't. So, it is the same way as it would be with a present tense!
It doesn't mean that present tenses and perfect tenses always behave the same because they are still affected by the reported speech.