Method getUserPrincipal in Websockets implementation for Glassfish is not working

Question

I have created a WebSocket with the JEE7 standard API. I have a class annotated with @ServerEndPoint and three methods annotated with @OnOpen, @OnClose and OnMessage. I´m deploying the application in a Glassfish v4 and it works but when I invoke the getUserPrincipal() method from some Session instance, it returns always null. This is the code I´m ussing to test it:

@ServerEndpoint(value = "/chat")
public class ChatServerEndpoint {

    private static final Logger LOG = LoggerFactory.getLogger(ChatServerEndpoint.class);

    @OnOpen
    public void onOpen(Session session) { 
        LOG.debug("Opening a session with id " + session.getId() + " for " + session.getUserPrincipal());
    }

    @OnClose
    public void onClose(Session session) { 
        LOG.debug("Closing the session " + session.getId() + " associated with " + session.getUserPrincipal());
    }

    @OnMessage
    public void onMessage(Session session, String msg) {
        LOG.debug("There are " + session.getOpenSessions().size() + " opened sessions");
        for (Session sess : session.getOpenSessions()) {
            LOG.debug("Session " + sess.getId() + " associated with " + sess.getUserPrincipal());
            try {
                sess.getBasicRemote().sendText(msg);
            } catch (IOException e) {
                LOG.error("Error sending message", e);
            }
        } 
    }
}

This code is as simple as possible to narrow the problem. This is the log output:

22:22:48.638 [http-listener-1(1)] DEBUG e.p.server.rs.ChatServerEndpoint - Opening a session with id 437a9b4d-c694-4a19-b912-47b88da4eb9a for null
22:22:54.350 [http-listener-1(5)] DEBUG e.p.server.rs.ChatServerEndpoint - There are 1 opened sessions
22:22:54.351 [http-listener-1(5)] DEBUG e.p.server.rs.ChatServerEndpoint - Session 437a9b4d-c694-4a19-b912-47b88da4eb9a associated with null
22:23:58.888 [http-listener-1(2)] DEBUG e.p.server.rs.ChatServerEndpoint - Closing the session 437a9b4d-c694-4a19-b912-47b88da4eb9a associated with null

I tried to make it work by including the websocket path in the web-resource-collection of the security-constraint for JAAS configuration (web.xml file) but in this case the access to the websocket from client side fails with a java.util.concurrent.TimeoutException after a while.

This is my web-app.xml file:

<web-app xmlns="http://java.sun.com/xml/ns/javaee"
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
          version="3.0">

        <welcome-file-list>
           <welcome-file>Ps.html</welcome-file>
        </welcome-file-list>

        <servlet>
            <servlet-name>jersey-serlvet</servlet-name>
            <servlet-class>com.sun.jersey.spi.container.servlet.ServletContainer</servlet-class>
            <load-on-startup>1</load-on-startup>
        </servlet>

        <servlet-mapping>
            <servlet-name>jersey-serlvet</servlet-name>
            <url-pattern>/rs/*</url-pattern>
        </servlet-mapping>

          <servlet>
              <servlet-name>upload</servlet-name>
              <servlet-class>es.ps.server.file.FileUploadServlet</servlet-class>
        </servlet>
        <servlet-mapping>
              <servlet-name>upload</servlet-name>
              <url-pattern>/upload</url-pattern>
        </servlet-mapping>

        <login-config>
            <auth-method>FORM</auth-method>
            <realm-name>psRealm</realm-name>
            <form-login-config>
                <form-login-page>/login.html</form-login-page>
                <form-error-page>/login.html?error=true</form-error-page>
            </form-login-config>
        </login-config>
        <security-constraint>
            <web-resource-collection>
                <web-resource-name>Secure Pages</web-resource-name>
                <description/>
                <url-pattern>*.html</url-pattern>
                <url-pattern>/Ps/*</url-pattern>
                <url-pattern>/rs/*</url-pattern>
                <url-pattern>/chat</url-pattern>
            </web-resource-collection>
            <auth-constraint>
                <role-name>ADMINISTRATOR</role-name>
            </auth-constraint>
        </security-constraint> 
    </web-app>

Somebody has had the same problem?

Thanks in advance.