The manual says:
The property name used to identify the message group is "_HQ_GROUP_ID"" (or the constant MessageImpl.HDR_GROUP_ID). Alternatively, you can set autogroup to true on the SessionFactory which will pick a random unique id.
There is no HDR_GROUP_ID defined in MessageImpl. Should it be org.hornetq.api.core.Message instead?
Also on the xml sample section under 31.5. JAAS Security Manager, the xml brackets is not displayed correctly.