This class handles the expanding of the "Package Type" or "Package Heading"
node. It will give a list of all the packages available in the schema.
author: Colin Bell
Create the child nodes for the passed parent node and return them. Note
that this method should not actually add the child nodes to the
parent node as this is taken care of in the caller.
Parameters: session - Current session. Parameters: node - Node to be expanded. A list of ObjectTreeNode objects representing the childnodes for the passed node.