logic:iterate 中的id与bean:write的name什么关系

为什么我输入的内容会显示出来的呢?action里面并没有bean而只有session
如果我输入"uu"那么也应该是在vctor的这个Users里呀,跟这个id有什么关系呢

<logic:present name="Users">
<logic:iterate id="e" name="Users">
<bean:write name="e"/><br>
</logic:iterate>
</logic:present>

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DynaActionForm addForm = (DynaActionForm) form;
String username = addForm.getString("username");
if (username == null || username.length() < 1)
mapping.getInputForward();
HttpSession session = request.getSession();
Vector users = (Vector) session.getAttribute("Users");
if (users == null)
users = new Vector();
users.addElement(username);
session.setAttribute("Users", users);
return mapping.findForward("indexGo");