`proxy` is not `Serializable` anymore in Clojure 1.9

(defn my-rich
"不行的方法 会报
The implementation of the RichFlatMapFunction is not serializable."
[]
(proxy [RichFlatMapFunction] []
(flatMap [value out]
(log/info "使用了proxy" value)
(let [tomap (into {} value)
{:keys [shopid shopname billdate] :as data} (read-string (get tomap "body"))]
(.collect out (Tuple3. (str shopid billdate) (str data) 1))
))
))
clojure 1.8.0 is ok
but 1.9 1.10.beat5 will
The implementation of the RichFlatMapFunction is not serializable