code: private void appendOptGroupLabel(final AppendingStringBuffer buffer, final T optGroup)
  	{
  		buffer.append("\n<optgroup label='")
  			.append(Strings.escapeMarkup(getOptGroupLabel(optGroup))).append("'>");
  	}
docs: Appends the label of the given opt group object to the given {@link AppendingStringBuffer}
  object.
  
  @param buffer
  the buffer
  @param optGroup
  the opt group to append.