Modify user details rest api endpoint does not update password

[Can4]

Hi,

I want to update user password. So I am using below address;

Modify User Detail 

I am using PUT v1/users/<user_id> and send below xml in the  body

<entry xmlns="http://www.w3.org/2005/Atom">
    <title type="text">user</title>
    <updated>2016-05-27T06:03:25.583Z</updated>
    <link href="http://test:6405/biprws/v1/users/12" rel="alternate" />
    <content type="application/xml">
        <attrs xmlns="http://www.sap.com/rws/bip">
           <attr name="newPassword" type="string">sampleNewPassword@!</attr> 
        </attrs>
    </content>
</entry>

When I send request with above data I am getting 200 but password not updating. I try to update other fields like description, fullname etc. this fields being updated. Documentation says; 

• Use <attr name="newPassword" type="string"></attr> to define password.

I am trying this but password still remains the same as before and is not updated with the new value I want it to be.

How can I fix this problem with sap bo rest api?