GenericCollectionElement.java

    private <T extends Element> T cache(T newElement)
    {
        ElementKey key = newElement.getKey();
        Element existingElement = _elements.get(key);
        if(existingElement != null)
            //Unchecked cast.
            return (T)existingElement;
        else
        {
            _elements.put(key, newElement);
            return newElement;
        }
    }