Yes, that is true. That is right now sadly not possible.
The reason for that is that it currently always does a JSON.parse in line 561. It would probably need a “useRawData” option like the MoveBinaryData-Node. Additionally, would it be needed to define a custom content-type, to set it in this case to “application/xml”. Any help there would be very appreciated!
While testing I noticed that the “Webhook Node” cannot handle non-json bodies.
I first created a “webhook”-workflow as recipient-bin for testing. I was never able to get the body.
I compared the requestOptions 1:1 to request-promise documentation and couldn’t see a difference.
So I sent it against one of the webhook-sites (requestbin etc.). There it worked just fine.
While I’m at it, I tried to extend the webhook-node to accept xml bodies, but I noticed that the parsing happens very deep in the core code of n8n.io. So I stopped.
Anyway, have a look at the extension to at least send raw-strings.