Is ghusl required if there is dampness in the underwear upon waking up, without remembering a wet dream or finding traces of semen?

What is seen on the garment after waking up and is doubted, one chooses between it being maniyy (seminal fluid), in which case one performs ghusl (ritual bath) for it, or madhy (pre-seminal fluid), in which case one washes what it has touched of the body and garment. This is the view of the Shafi'i school and what is given as fatwa.