any propagation for ClassT lower bound
any propagation for ClassT lower bound

Summary: classT is covariant

Reviewed By: samwgoldman

Differential Revision: D10501345

fbshipit-source-id: 2b974312a620474defb549ad7f2129c162b49c02

nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow