code: private void appendDetailedString(int level, StringBuilder stringBuilder) {
      String pad = Strings.repeat("--", level);
      stringBuilder.append(pad).append(this).append(SystemUtils.LINE_SEPARATOR);
      for (ProductPartitionNode childNode : getChildren()) {
        childNode.appendDetailedString(level + 1, stringBuilder);
      }
    }
docs: Appends to {@code stringBuidler} a String representation of this node and all of its children.
  
  @param level the level of this node
  @param stringBuilder the StringBuilder to append to