func registerSTSRouter(router *mux.Router) {
	// Initialize STS.
	sts := &stsAPIHandlers{}

	// STS Router
	stsRouter := router.NewRoute().PathPrefix(SlashSeparator).Subrouter()

	// Assume roles with no JWT, handles AssumeRole.
	stsRouter.Methods(http.MethodPost).MatcherFunc(func(r *http.Request, rm *mux.RouteMatch) bool {
		ctypeOk := wildcard.MatchSimple("application/x-www-form-urlencoded*", r.Header.Get(xhttp.ContentType))

			h.Reset()
			h.Write([]byte(provCfg.ClientSecret))
			hashedSecret = base64.RawURLEncoding.EncodeToString(h.Sum(nil))
		}
		if arn != DummyRoleARN {
			if res.Roles == nil {
				res.Roles = make(map[string]madmin.OpenIDProviderSettings)
			}
			res.Roles[arn.String()] = madmin.OpenIDProviderSettings{
				ClaimUserinfoEnabled: provCfg.ClaimUserinfo,
				RolePolicy:           provCfg.RolePolicy,