who brought up the idea of a black hole at planck length?

metageg

does anyone know who first mentioned, that by measuring physics at very small length scales (bearing in mind the spactime manifold), one will arrive at a black hole somewhere near the planck scale which prevents one from taking the measurements to even smaller lengths (because events inside the schwarzschildradius are not physically observable from the outside)?
i know that riemann was maybe the first to proclaim that physics as we now it may not be valid at "the infinitely small" (his habilitation lecture in 1854) and some leads indicate that J.A.Wheeler is connected to my question, but i dont know how to prove its him or find out the true origin:(

thanks for your help!