types/src/main/java/com/google/common/html/types/SafeHtmlBuilder.java
public SafeHtmlBuilder appendContent(Iterator<SafeHtml> htmls) {
    checkNotVoidElement();
    while (htmls.hasNext()) {
      contents.add(htmls.next());
    }
    return this;
  }
public SafeHtmlBuilder appendContent(Iterator<SafeHtml> htmls) {
    checkNotVoidElement();
    while (htmls.hasNext()) {
      contents.add(htmls.next());
    }
    return this;
  }
Appends the given {@code htmls} as this element's content, in the sequence the Iterator returns
them.

@throws IllegalStateException if this builder represents a void element