001    package org.nakedobjects.applib.events;
002    
003    import org.nakedobjects.applib.Identifier;
004    
005    
006    /**
007     * Represents a check to determine whether a member of an object is usable or has been disabled.
008     * 
009     * <p>
010     * If {@link #getReason()} is <tt>null</tt>, then is usable; otherwise is disabled.
011     * 
012     * @see AccessEvent
013     * @see VisibilityEvent
014     * @see ValidityEvent
015     */
016    public abstract class UsabilityEvent extends InteractionEvent {
017    
018        private static final long serialVersionUID = 1L;
019    
020        public UsabilityEvent(final Object source, final Identifier identifier) {
021            super(source, identifier);
022        }
023    
024    }