#vulnerable code 
                                @Override
    public Property getContainerProperty(Object itemId, Object propertyId) {
        return getItem(itemId).getItemProperty(propertyId);
    } 
                            #location 3 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                @Override
    public Property getContainerProperty(Object itemId, Object propertyId) {
        Item i = getItem(itemId);
        return (i != null) ? i.getItemProperty(propertyId) : null;
    }