code: @PropertySetter("allowCustom")
      public void setAllowCustom(boolean allowCustom) {
          customItem.setVisible(allowCustom);
          
          if (!allowCustom) {
              BaseComponent sibling;
              
              while ((sibling = customItem.getNextSibling()) != null) {
                  sibling.destroy();
              }
          }
      }
docs: If set to true, the user may select "Custom..." from the choice list and enter a custom date
  range. If set to false, this choice is hidden and any existing custom entries are removed
  from the list.
  
  @param allowCustom Determines whether or not custom entries are allowed.