Unable to obtain expiration time of refresh tokens about fosite

[mitar]

I added to my introspect endpoint handler:

	if ir.GetTokenUse() == "refresh_token" {
		w.Header().Set("Content-Type", "application/json;charset=UTF-8")
		w.Header().Set("Cache-Control", "no-store")
		w.Header().Set("Pragma", "no-cache")

		if !ir.IsActive() {
			_ = json.NewEncoder(w).Encode(&struct {
				Active bool `json:"active"`
			}{Active: false})
			return
		}

		response := map[string]interface{}{
			"active": true,
		}

		if !ir.GetAccessRequester().GetSession().GetExpiresAt(fosite.RefreshToken).IsZero() {
			response["exp"] = ir.GetAccessRequester().GetSession().GetExpiresAt(fosite.RefreshToken).Unix()
		}

		_ = json.NewEncoder(w).Encode(response)
		return
	}