[APP][Pro] HTTP request flow cards - HTTP request triggers, conditions and actions for flows

Thank you! But when I try:

{"method":"post","protocol":"http:","hostname":"openhab","port":8080,"path":"/rest/items/RaffstoresAlle","headers":{"Content-Type":"text/plain","Accept":"application/json"}}

I get an error message:

Flow Card Error: 400

grafik

Do you know why?