code: public GridBagLayoutBuilder appendSeparator(String labelKey) {
          if (this.currentRowList.size() > 0) {
              nextLine();
          }
          final JComponent separator = getComponentFactory().createLabeledSeparator(labelKey);
          return append(separator, 1, 1, true, false).nextLine();
      }
docs: Appends a seperator (usually a horizonal line) using the provided string
  as the key to look in the
  {@link #setComponentFactory(ComponentFactory) ComponentFactory's}message
  bundle for the text to put along with the seperator. Has an implicit
  {@link #nextLine()}before and after it.
  
  @return "this" to make it easier to string together append calls