How to get a byte aray payload when using weh-hook's publish action

[alwyngo]

What I config in emqx_web_hook.conf is like web.hook.rule.message.publish.2 = {"action": "on_message_publish", "topic": "foo/#"} When the server receviced the map data, the payload field's type is String not a byte array, the message is messy code like this ���f}����@@@, what can I do to get a byte array payload?

[alwyngo]

if possible to accept it with ByteBuffer or other data type?