code: public static <E> List<E> intersection(final List<E> list1, final List<E> list2) {
          final List<E> result = newArrayList();
          for (final E item : list1) {
              if (list2.contains(item)) {
                  result.add(item);
              }
          }
          return result;
      }
docs: /*
  Documented, #intersection