Don't know how to iterate over supplied "items" in <forEach>

JSTL的标签  <c:forEach> 里的items属性被赋予了一个无法遍历的对象。

LableManager label=(LableManager) service.findeById(id);
List<LableManager> labels = new ArrayList<LableManager>();
labels.add(label);
session.setAttribute("lable",labels);