code: @SuppressWarnings("unchecked")
  	public static <T> Set<T> constructSortedSetForProperty(Collection<T> aCollection,
  	String aPropertyName)
  	throws Exception
  	{
  		if (aCollection == null || aCollection.isEmpty())
  			return null;
  
  		Set<T> set = new TreeSet<T>();
  		Object bean = null;
  		for (Iterator<T> i = aCollection.iterator(); i.hasNext();)
  		{
  			bean = (Object) i.next();
  			set.add((T) JavaBean.getProperty(bean, aPropertyName));
  		}
  
  		return set;
  	}
docs: @param aPropertyName
  the property name
  @param aCollection
  the collection to construct set from (this object) must have
  an javaBean property that matches aPropertyName
  @param <T>
  the type class
  @return set of bean properties (HashSet)
  @throws Exception
  when an unknown error occurs