code: void assertPhrasingContent() throws InvalidInputException {
      assertContentModel(Arrays.asList(TextNode.class, Link.class, Chime.class, Bold.class, Italic.class, Image.class,
          LineBreak.class, Span.class, Emoji.class, HashTag.class, CashTag.class, Mention.class));
    }
docs: Check that the element's children are limited to phrasing content.
  @throws InvalidInputException