lua_http.request uploadContent无法提交数据

[d1bug]

无论我怎么改变uploadContent的内容，后台始终无法收到内容

laoxie.ajax = function (params,callback)
params = params or {}
local headers= {
["Content-Type"] = "application/x-www-form-urlencoded",
}
lua_http.request({
url = params.url,
isPost=true,
uploadContent=params.param,
headers=headers,
--body=params.param,
onResponse = function (response)
if response.http_code ~= 200 then
if callback then
callback(nil)
end
else
if callback then
callback(response.response)
end
end
end}
)
end

[d1bug]

用headers传参没问题