onContentSniffed  
  fun onContentSniffed(connectFlags: <Error class: unknown class> = ConnectFlags(0u), handler: (type: String, <Error class: unknown class>) -> Unit): <Error class: unknown class>(source)
This signal is emitted after signal@Message::got-headers.
If content sniffing is disabled, or no content sniffing will be performed, due to the sniffer deciding to trust the Content-Type sent by the server, this signal is emitted immediately after signal@Message::got-headers, and @type is null.
Parameters
connectFlags 
a combination of ConnectFlags
handler
the Callback to connect. Params: type the content type that we got from sniffing; params a #GHashTable with the parameters