@SuppressWarnings("unchecked")
Map<String, SessionAttribute> attrs = getFieldValue(session, "attrs", Map.class);
session.setAttribute("count", 0);
SessionAttribute attr = attrs.get("count");
assertTrue(attr.isModified());
requestContexts.commitRequestContext(requestContext);
assertSame(attr, attrs.get("count"));
assertFalse(attr.isModified()); // 提交以后，modified被复位
}