Seam Booking example errors on concurrent ajax requests

Seam Booking example "main.seam" page has a search field which updates results via richfaces ajax requests, but it doesn't use a4j:queue, so multiple concurrent requestes on the same page may occur. This may cause various errors, depending on the timing of the requests.

These errors have been spotted while running the slink test on cluster:

1. java.lang.IllegalArgumentException: factory method with defined scope outjected a value: org.jboss.seam.core.conversationList
2. java.lang.RuntimeException: Failure to marshal argument(s), caused by
java.util.ConcurrentModificationException
3. java.lang.IllegalArgumentException: attempt to create merge event with null entity

(note that I have been able to reproduce at least the error 3 also on previous EAP5.1 versions with the same test and error 1 on previous versions in a similar scenario. I believe error 2 occurs because the example doesn't set com.sun.faces.serializeServerState to true, as sugggested in Seam documentation)