报错 ：：There is no getter for property ......

按照老师的代码来写的

<mapper namespace="com.damu.entity.Users">

  <select id="findUsers" resultType="com.damu.entity.Users">

    <select id="findUsers" resultMap="forUsers">

        select * from users

         <if test="id != null">

            where id = #{id}

        </if>

    </select>

</mapper>

报错：There is no getter for property named 'id' in 'class java.lang.Integer

在实体类中也写了仅有id参数的构造函数，为啥还是报错呢？？？？？