Data conversion exceptions

[anviod]

1 Run hmq
2 run MQTTx
set payload：HEX QoS：0
topic ：/things/test/up
payload：AABBCC

ERROR

plugins/bridge

this is Kafka Payload

{"clientid":"mqtt_client","username":"mqtt_client","topic":"/things/test/up","payload":"\ufffd\ufffd\ufffd","ts":1614240899,"size":0,"action":"publish"}

[anviod]

AABBCC -> "\ufffd\ufffd\ufffd"