MyBatis多表联查返回List仅一条数据？主键冲突BUG排查与解决方案

SELECT
    a.id,
    a.username,
    r.id,
    r.role_name,
    r.role_desc,
    p.id,
    p.permission_name,
    p.url
FROM
    `admin` a
    LEFT JOIN admin_role ON a.id = admin_role.aid
    LEFT JOIN `role` r ON admin_role.rid = r.id
    LEFT JOIN role_permission ON r.id = role_permission.rid
    LEFT JOIN permission p ON role_permission.pid = p.id
WHERE
    a.id = #{aid}

<resultMap id="adminMapper" type="com.lion.online.pojo.Admin">
    <id property="id" column="id"></id>
    <result property="username" column="username"></result>
    <!-- 角色列表关联 -->
    <collection property="roles" column="id" ofType="com.lion.online.pojo.Role">
        <id property="id" column="id"></id>
        <result property="roleName" column="role_name"></result>
        <result property="roleDesc" column="role_desc"></result>
        <!-- 权限列表关联 -->
        <collection property="permissions" column="id" ofType="com.lion.online.pojo.Permission">
            <id property="id" column="id"/>
            <result property="permissionName" column="permission_name"></result>
            <result property="url" column="url"></result>
        </collection>
    </collection>
</resultMap>

SELECT
    a.id,
    a.username,
    r.id AS rid,  -- 角色ID别名
    r.role_name,
    r.role_desc,
    p.id AS pid,  -- 权限ID别名
    p.permission_name,
    p.url
FROM
    `admin` a
    LEFT JOIN admin_role ON a.id = admin_role.aid
    LEFT JOIN `role` r ON admin_role.rid = r.id
    LEFT JOIN role_permission ON r.id = role_permission.rid
    LEFT JOIN permission p ON role_permission.pid = p.id
WHERE
    a.id = #{aid}

<resultMap id="adminMapper" type="com.lion.online.pojo.Admin">
    <!-- 管理员主表映射 -->
    <id property="id" column="id"></id>
    <result property="username" column="username"></result>
    <!-- 角色列表关联：column指向角色ID别名rid -->
    <collection property="roles" column="rid" ofType="com.lion.online.pojo.Role">
        <id property="id" column="rid"></id>  <!-- 角色主键映射别名列 -->
        <result property="roleName" column="role_name"></result>
        <result property="roleDesc" column="role_desc"></result>
        <!-- 权限列表关联：column指向权限ID别名pid -->
        <collection property="permissions" column="pid" ofType="com.lion.online.pojo.Permission">
            <id property="id" column="pid"/>  <!-- 权限主键映射别名列 -->
            <result property="permissionName" column="permission_name"></result>
            <result property="url" column="url"></result>
        </collection>
    </collection>
</resultMap>