HTTP Management interface "IllegalArgumentException: Invalid string contents" where realm has key and trust store but interface does not have https

Using a security realm with a key and trust store defined causes the following error to be reported when the http interface is accessed if no https socket binding is also specified: -

ERROR [io.undertow.request] (XNIO-1 read-3) UNDERTOW005001: An exception occurred processing the request: java.lang.IllegalArgumentException: Invalid string contents