You are correct. I pulled up the code for myself. A network interruption is interpreted as if there is a typo in jboss-esb.xml and the entire ESB deployment fails without any useful information getting logged.
I managed to get my own implementation of SOAPProxy running that delays initialization until a message is proxied, and treats a not-currently-running server as a temporary message processing error. I also added some try/catch/throw blocks so I can at least get a clue why something might not be working.
In order to satisfy the GPL, can you or someone else offer some advice on where to post the code?
I did get confused with the part that the "?wsdl" style URL is not supported. The proxy code is really hoping for an incoming SOAP message.