code: public final boolean isItemEnabled(final int index) {
          AbstractItem item = items.get(index);
          return item instanceof Item && ((Item) item).isEnabled();
      }
docs: Returns, whether the item at a specific index is enabled, or not.
  
  @param index
  The index of the item, which should be checked, as an {@link Integer} value
  @return True, if the item is enabled, false otherwise