mod_http_oauth2: Stricten check of urlencoded form data Because type(formdecode("string without equals sign")) == "string", so best avoid continuing in that case, even if strings mostly behave as tables as long as you don't hit one of the __index methods.

This module helps make BOSH and WebSocket connection endpoints
discoverable via the HTTP method described in
[XEP-0156](https://xmpp.org/extensions/xep-0156.html#http).