apocrypha - What is the Testament of Hezekiah? I know it exists, but can't locate it

I am currently reading up on of apocryphal and pseudopigagraphical literature, and I see on a list that the Testament of Hezekiah is enumerated as one of them. However, I cannot locate a source or any short blurb on its date, origin, and content? Do any of you know? Thanks!