Reflection warning in clojure.reflect

We introduced some unintentional reflection in the new Java reflect datafy changes. If you set warn-on-reflection to true it shows up as:

Basically the new typeref->class lost the Class marker introducing reflection.

Proposed: Type hint the return of typeref->class.

Patch: clj-2436.patch - add set! of warn-on-reflection, type hint return of typeref->class, fix indent on one line.