Starting from a node, searches down the hierarchy to look for a node that contains a specific value.
It works only with nodes of type DefaultMutableTreeNode.
The searched value is the second element of a String[] that is the userObject of the node.
Returns the TreePath of the found node, null if the node has not been found
Parameters:
node - The starting node
nodeValue - The value of the node to search for
Returns:
TreePath The TreePath of the node that contains the value, null if such a node is not found