src/main/java/org/jboss/util/property/PropertyMap.java
public void addPropertyListener(PropertyListener listener)
   {
      if (listener == null)
         throw new NullArgumentException("listener");

      if (listener instanceof BoundPropertyListener)
      {
         addPropertyListener((BoundPropertyListener) listener);
      }
      else
      {
         // only add the listener if it is not in the list already
         if (!unboundListeners.contains(listener))
            unboundListeners.add(listener);
      }
   }
public void addPropertyListener(PropertyListener listener)
   {
      if (listener == null)
         throw new NullArgumentException("listener");

      if (listener instanceof BoundPropertyListener)
      {
         addPropertyListener((BoundPropertyListener) listener);
      }
      else
      {
         // only add the listener if it is not in the list already
         if (!unboundListeners.contains(listener))
            unboundListeners.add(listener);
      }
   }
Add a property listener.

@param listener   Property listener to add.