code: public String saveToString(List<Object> list) {
          StringBuilder sb = new StringBuilder();
          for(Object obj : list) {
              if (obj == null) {
                  continue;
              } else if (obj instanceof AbstractJaxb) {
                  sb.append(this.saveToString((AbstractJaxb) obj));
              } else {
                  sb.append(obj.toString());
              }
          }
          return sb.toString();
      }
docs: <p>
  marshal the inner objects of tag to string and return it.
  </p>
  <pre>
  &lt;-- html --&gt;
  &lt;div id="foo"&gt;aaa&lt;span&gt;bbb&lt;/span&gt;ccc&lt;/div&gt;
  </pre>
  <pre>
  // code
  List&lt;Object&gt; list = html.getById("foo", Div.class).getContent();
  String contents = mixer2Engine.saveToString(list);
  // "contents" has "aaa&lt;span&gt;bbb&lt;/span&gt;ccc"
  </pre>
  
  @param list
  @return