code: public SafeHtmlBuilder setSrcdoc(SafeHtml value) {
      if (!SRCDOC_SAFE_HTML_ELEMENT_WHITELIST.contains(elementName)) {
        throw new IllegalArgumentException(
            "Attribute \"srcdoc\" with a SafeHtml value can only be used "
                + "by one of the following elements: "
                + SRCDOC_SAFE_HTML_ELEMENT_WHITELIST);
      }
      return setAttribute("srcdoc", value.getSafeHtmlString());
    }
docs: Sets the {@code srcdoc} attribute for this element.
  
  <p>The attribute {@code srcdoc} with a {@code SafeHtml} value is allowed on these elements:
  
  <ul>
  <li>{@code iframe}
  </ul>
  
  @throws IllegalArgumentException if the {@code srcdoc} attribute with a {@code SafeHtml} value
  is not allowed on this element