在jsondeserializat中获取错误ionschema:jsondeserializationschema cannot 解析为类型

DataStream<ObjectNode> messageStream = env.addSource(
                    new FlinkKafkaConsumer09<>("test2"
                            , new**JSONDeserializationSchema()**,properties));

            messageStream.rebalance().map(new MapFunction<ObjectNode, String>() {
                private static final long serialVersionUID = -6867736771747690202L;

                @Override
                public String map(ObjectNode value) throws Exception {
                    return "Kafka and Flink says: " + value.get("key").asText();
                }
            }).print();