code: public List<TextNode> textNodes() {
          List<TextNode> textNodes = new ArrayList<>();
          for (Node node : childNodes) {
              if (node instanceof TextNode)
                  textNodes.add((TextNode) node);
          }
          return Collections.unmodifiableList(textNodes);
      }
docs: Get this element's child text nodes. The list is unmodifiable but the text nodes may be manipulated.
  <p>
  This is effectively a filter on {@link #childNodes()} to get Text nodes.
  @return child text nodes. If this element has no text nodes, returns an
  empty list.
  </p>
  For example, with the input HTML: {@code <p>One <span>Two</span> Three <br> Four</p>} with the {@code p} element selected:
  <ul>
  <li>{@code p.text()} = {@code "One Two Three Four"}</li>
  <li>{@code p.ownText()} = {@code "One Three Four"}</li>
  <li>{@code p.children()} = {@code Elements[<span>, <br>]}</li>
  <li>{@code p.childNodes()} = {@code List<Node>["One ", <span>, " Three ", <br>, " Four"]}</li>
  <li>{@code p.textNodes()} = {@code List<TextNode>["One ", " Three ", " Four"]}</li>
  </ul>