code: public synchronized Boolean isChecked(int index) {
          if(index < 0 || index >= itemStatus.size())
              return null;
  
          return itemStatus.get(index);
      }
docs: Checks if a particular item is part of the check box list and returns a boolean value depending on the toggle
  state of the item.
  @param index Index of the item to check the status of
  @return If the index was not valid in the list box, {@code null} is returned, otherwise {@code true} or
  {@code false} depending on checked state of the item at that index