Indicates that the container has rejected a request because a concurrent
request is associated with the same conversation context.
The container ensures that a long-running conversation may be associated with
at most one request at a time, by blocking or rejecting concurrent requests.
If the container rejects a request, it must associate the request with a new
transient conversation and throw an exception of type
BusyConversationException from the restore view phase of the JSF
lifecycle.