code: public synchronized Boolean isChecked(V object) {
          if(indexOf(object) == -1)
              return null;
  
          return itemStatus.get(indexOf(object));
      }
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 object Object to check the status of
  @return If the item wasn't found in the list box, {@code null} is returned, otherwise {@code true} or
  {@code false} depending on checked state of the item