code: public static <T extends AbstractJaxb> void removeDescendants(T target,
              String clazz, Class<T> tagType) {
          execute(target, tagType, clazz);
      }
docs: タグとclass指定で子孫要素を削除する
  
  @param <T>
  tag class type. (i.e. Div.class, Span.class...)
  @param target
  objects for scan
  @param clazz
  class property of tag
  @param tagType
  tag class