Excludes WeakValueMap from the serializable test #12401

Also added a note to the WeakValueMap JavaDoc stating that it is
not serializable.

Change-Id: If342746ad7c7cac0db8bac4ba75236970cc4cd01

server/src/com/vaadin/util/WeakValueMap.java

@@ -30,6 +30,8 @@ import java.util.Set;
  * A Map holding weak references to its values. It is internally backed by a
  * normal HashMap and all values are stored as WeakReferences. Garbage collected
  * entries are removed when touched.
+ * <p>
+ * <em>Note</em> this class is not serializable.
  * 
  * @author Vaadin Ltd
  * @since 7.1.4

server/tests/src/com/vaadin/tests/server/TestClassesSerializable.java

@@ -65,6 +65,7 @@ public class TestClassesSerializable extends TestCase {
             "com\\.vaadin\\.util\\.ConnectorHelper", //
             "com\\.vaadin\\.server\\.VaadinSession\\$FutureAccess", //
             "com\\.vaadin\\.external\\..*", //
+            "com\\.vaadin\\.util\\.WeakValueMap.*", //
     };
 
     /**