Header is in post request

Hi.

Trying to set the message header Content-Type but I can not get it to work.
my code looks like this

msg.payload = {"action":"ARM_REQUEST"},
msg.headers = {"Content-Type":"application/vnd.assaabloy.arx.integrated-alarm-1.0+json"};
msg.headers = {Accept:"application/vnd.assaabloy.arx.integrated-alarm-1.0+json"};

return msg;

Attach a screenshot from wireshark

screen

Any idea how to set Content-Type Correct?

You are setting msg.headers to one value, then immediately overwritting it with another. Perhaps you meant the second one to add the Accept property rather than throwing away the Content Type property.
msg.headers.Accept = "application/vnd.assaabloy.arx.integrated-alarm-1.0+json"