Use APPLICATION_SCOPE for the session lock (#11792)

The Vaadin session itself is also stored in APPLICATION_SCOPE. The default
scope is PORTLET_SCOPE, so lock would be otherwise not be in sync with
the session.

To be able to do this, relevant methods in VaadinService are made protected so
that VaadinPortletService can override them.

Fixes #11611

server/src/main/java/com/vaadin/server/VaadinPortletService.java

 import java.io.InputStream;
 import java.net.URL;
 import java.util.List;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
         getWrappedPortletSession(wrappedSession).removeAttribute(
                 getSessionAttributeName(), PortletSession.APPLICATION_SCOPE);
     }
+
+    @Override
+    protected void setSessionLock(WrappedSession wrappedSession, Lock lock) {
+        if (wrappedSession == null) {
+            throw new IllegalArgumentException(
+                    "Can't set a lock for a null session");
+        }
+        Object currentSessionLock = getWrappedPortletSession(wrappedSession)
+                .getAttribute(getLockAttributeName(),
+                        PortletSession.APPLICATION_SCOPE);
+        assert (currentSessionLock == null
+                || currentSessionLock == lock) : "Changing the lock for a session is not allowed";
+
+        getWrappedPortletSession(wrappedSession).setAttribute(
+                getLockAttributeName(), lock,
+                PortletSession.APPLICATION_SCOPE);
+    }
+
+    @Override
+    protected Lock getSessionLock(WrappedSession wrappedSession) {
+        Object lock = getWrappedPortletSession(wrappedSession)
+                .getAttribute(getLockAttributeName(),
+                        PortletSession.APPLICATION_SCOPE);
+
+        if (lock instanceof ReentrantLock) {
+            return (ReentrantLock) lock;
+        }
+
+        if (lock == null) {
+            return null;
+        }
+
+        throw new RuntimeException(
+                "Something else than a ReentrantLock was stored in the "
+                        + getLockAttributeName() + " in the session");
+    }
 }

server/src/main/java/com/vaadin/server/VaadinService.java

      * @param lock
      *            The lock object
      */
-    private void setSessionLock(WrappedSession wrappedSession, Lock lock) {
+    protected void setSessionLock(WrappedSession wrappedSession, Lock lock) {
         if (wrappedSession == null) {
             throw new IllegalArgumentException(
                     "Can't set a lock for a null session");
      *
      * @return The attribute name for the lock
      */
-    private String getLockAttributeName() {
+    protected String getLockAttributeName() {
         return getServiceName() + ".lock";
     }
 

server/src/test/java/com/vaadin/server/VaadinPortletServiceTest.java

 
 import java.util.concurrent.locks.ReentrantLock;
 
+import javax.portlet.PortletSession;
+
 import org.junit.Before;
 import org.junit.Test;
 import org.mockito.Mockito;
             ReentrantLock mockLock = Mockito.mock(ReentrantLock.class);
             when(mockLock.isHeldByCurrentThread()).thenReturn(true);
 
-            WrappedSession emptyWrappedSession = Mockito
+            WrappedPortletSession emptyWrappedSession = Mockito
                     .mock(WrappedPortletSession.class);
-            when(emptyWrappedSession.getAttribute("null.lock"))
+            when(emptyWrappedSession.getAttribute("null.lock",PortletSession.APPLICATION_SCOPE))
                     .thenReturn(mockLock);
             VaadinRequest requestWithUIIDSet = Mockito
                     .mock(VaadinRequest.class);