/** Propety set with node description. */
private static Sheet.Set psDesc;

/** Returns (and create if needed) new property set with a node description.
* @return new property set */        
private static final Sheet.Set getNodeDescSet () {

    if (psDesc==null) {
        psDesc = new Sheet.Set ();

        // name of a set
        psDesc.setName ("NodeDescription");
        psDesc.put (new PropertySupport.ReadOnly (

            // the unique name of property with node description
            "node_description", // NO18N

            String.class,
            "Node description", // NOI18N
            "Message describes type and purpose of node." // NOI18N
        ) {
                public Object getValue () {
                    // text desribes this node
                    return "This is a mount node, the parent of mounted filesystem.";
                }
            });

        // this set is hidden
        psDesc.setHidden (true);
    }
    return psDesc;
}

public PropertySet[] getPropertySets () {
    // add propetry set with a node description

    // get old property sets
    ArrayList l = (ArrayList)Arrays.asList (super.getPropertySets ());

    // add getNodeDescSet
    l.add (getNodeDescSet ());

    // return new array
    return l.toArray ();
}