code: private void addCheckBox(final String internalValue, String labelMessageKey) {
  
          CmsCheckBox box = new CmsCheckBox(Messages.get().key(labelMessageKey));
          box.setInternalValue(internalValue);
          box.addValueChangeHandler(new ValueChangeHandler<Boolean>() {
  
              public void onValueChange(ValueChangeEvent<Boolean> event) {
  
                  if (handleChange()) {
                      m_controller.weeksChange(internalValue, event.getValue());
                  }
              }
          });
          m_weekPanel.add(box);
          m_checkboxes.add(box);
  
      }
docs: Creates a check box and adds it to the week panel and the checkboxes.
  @param internalValue the internal value of the checkbox
  @param labelMessageKey key for the label of the checkbox