FailoverEndpoint can have multiple child endpoints. It will always try to send messages to
current endpoint. If the current endpoint is failing, it gets another active endpoint from the
list and make it the current endpoint. Then the message is sent to the current endpoint and if
it fails, above procedure repeats until there are no active endpoints. If all endpoints are
failing and parent endpoint is available, this will delegate the problem to the parent endpoint.
If parent endpoint is not available it will pop the next FaultHandler and delegate the problem
Endpoints that contain other endpoints should implement this method. It will be called if a
child endpoint causes an exception. Action to be taken on such failure is up to the implementation.
But it is good practice to first try addressing the issue. If it can't be addressed propagate the
exception to parent endpoint by calling parent endpoint's onChildEndpointFail(...) method.