how to post json by request url,it seems does not support send json params

[Wangxiaobin123]

local res, err = httpc:request_uri("XXXX", { ssl_verify = false, keepalive_timeout = 2000, method = "POST", body = cjson.encode("{"token":"aaa"}"), headers = { ["Content-Type"] = "application/json;charset=UTF-8" } })