EDIT

import java.util.HashSet;

import java.util.Set;

    /**

     * Adds an item to a set of <code>this</code> object and fires the according

     * {@link PropertyChangeEvent}. Workaround as long as add and remove is not yet

     * implemented in aspectJ.

     * @param set the set the new item is added to

     * @param newItem the new item to be added to the set

     * @param propertyName the name of the set as property in <code>this</code> object

     */

    protected <T extends CdmBase> void addToSetWithChangeEvent(Set<T> set, T newItem, String propertyName ){

        Set<T> oldValue = new HashSet<T>(set);

        set.add(newItem);

        firePropertyChange(new PropertyChangeEvent(this, propertyName, oldValue, set));

    }

    /**

     * Removes an item from a set of <code>this</code> object and fires the according

     * {@link PropertyChangeEvent}. Workaround as long as add and remove is not yet

     * implemented in aspectJ.

     * @param set the set the item is to be removed from

     * @param itemToRemove the item to be removed from the set

     * @param propertyName the name of the set as property in <code>this</code> object

     */

    protected <T extends CdmBase> void removeFromSetWithChangeEvent(Set<T> set, T itemToRemove, String propertyName ){

        Set<T> oldValue = new HashSet<T>(set);

        set.remove(itemToRemove);

        firePropertyChange(new PropertyChangeEvent(this, propertyName, oldValue, set));

    }