The income of a trust shall be included in computing the net income of the grantor of such trust where at any time the power to revest in the grantor title to any part of the corpus of the trust is vested:
(1) In the grantor, either alone or in conjunction with any person not having a substantial adverse interest in the disposition of such part of the corpus or the income therefrom; or
(2) In any person not having a substantial adverse interest in the disposition of such part of the corpus or the income therefrom.