public void deleteGroupPreProcess(@Nonnull final Group group)
    {
        // Fire event.
        GroupEventDispatcher.dispatchEvent(group, GroupEventDispatcher.EventType.group_deleting, Collections.emptyMap());
    }
Dispatches events that reflect an existing group having been deleted.

This method is intended to be invoked to update the internal state of GroupManager just before a group will be
deleted. It should rarely be invoked by code that is not part of the GroupManager implementation.

@param group The group that is about to be removed.
xmppserver/src/main/java/org/jivesoftware/openfire/group/GroupManager.java