* if enabled, it will make sure client secret is bcrypted correctly * if not, it falls back to old behaviour that allowing empty client secret and comparing plain text, though now it will do ConstantTimeCompare to avoid a timing attack. So in either way it should provide more secure of client secret verification. Co-authored-by: Alex Surraci <suraci.alex@gmail.com> Signed-off-by: Rui Yang <ruiya@vmware.com>