This represents the root of the repository.xml tree model. It contains
the ClassDescriptor objects for this repository and the default JDBC
connection.
author: Florian Bruckner version: $Id: OjbMetaRootNode.java,v 1.1.2.1 2005/12/21 22:32:38 tomdz Exp $
Purpose of this method is to fill the children of the node. It should
replace all children in alChildren (the arraylist containing the children)
of this node and notify the TreeModel that a change has occurred.
Return the descriptor object this node is associated with. E.g. if the
node displays a class descriptor, the ClassDescriptor describing the class
should be returned. Used for creating a Transferable. Null in this case
because the root doesn't have any associated objects.