criterion map now generated from annotations from server side counterpart

svn changeset:11350/svn branch:6.3_dd

24 files changed, 86 insertions, 79 deletions

diff --git a/src/com/vaadin/event/dd/acceptCriteria/AcceptAll.java b/src/com/vaadin/event/dd/acceptCriteria/AcceptAll.java
index 4424447d97..93a28a4d99 100644
--- a/src/com/vaadin/event/dd/acceptCriteria/AcceptAll.java
+++ b/src/com/vaadin/event/dd/acceptCriteria/AcceptAll.java
@@ -4,7 +4,9 @@
 package com.vaadin.event.dd.acceptCriteria;
 
 import com.vaadin.event.dd.DragAndDropEvent;
+import com.vaadin.terminal.gwt.client.ui.dd.VAcceptAll;
 
+@ClientCriterion(VAcceptAll.class)
 public final class AcceptAll extends ClientSideCriterion {
 
     private static AcceptCriterion singleton = new AcceptAll();
diff --git a/src/com/vaadin/event/dd/acceptCriteria/AcceptCriterion.java b/src/com/vaadin/event/dd/acceptCriteria/AcceptCriterion.java
index 24b0d9f2b8..1029e51baa 100644
--- a/src/com/vaadin/event/dd/acceptCriteria/AcceptCriterion.java
+++ b/src/com/vaadin/event/dd/acceptCriteria/AcceptCriterion.java
@@ -3,13 +3,15 @@
  */
 package com.vaadin.event.dd.acceptCriteria;
 
+import java.io.Serializable;
+
 import com.vaadin.event.Transferable;
 import com.vaadin.event.dd.DragAndDropEvent;
 import com.vaadin.event.dd.DropHandler;
 import com.vaadin.terminal.PaintException;
 import com.vaadin.terminal.PaintTarget;
 
-public interface AcceptCriterion {
+public interface AcceptCriterion extends Serializable {
 
     /**
      * Criterion that can be used create policy to accept/discard dragged
diff --git a/src/com/vaadin/event/dd/acceptCriteria/And.java b/src/com/vaadin/event/dd/acceptCriteria/And.java
index 29a4a6aa2e..91144771f9 100644
--- a/src/com/vaadin/event/dd/acceptCriteria/And.java
+++ b/src/com/vaadin/event/dd/acceptCriteria/And.java
@@ -11,6 +11,7 @@ import com.vaadin.terminal.PaintTarget;
  * TODO consider replacing this with Union
  * 
  */
+@ClientCriterion(com.vaadin.terminal.gwt.client.ui.dd.VAnd.class)
 public class And extends ClientSideCriterion {
     /**
      * 
diff --git a/src/com/vaadin/event/dd/acceptCriteria/ClientCriterion.java b/src/com/vaadin/event/dd/acceptCriteria/ClientCriterion.java
new file mode 100644
index 0000000000..ebc58bcbe3
--- /dev/null
+++ b/src/com/vaadin/event/dd/acceptCriteria/ClientCriterion.java
@@ -0,0 +1,22 @@
+package com.vaadin.event.dd.acceptCriteria;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import com.vaadin.terminal.gwt.client.ui.dd.VAcceptCriteria;
+
+/**
+ * TODO
+ * 
+ * @since 6.2
+ */
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.TYPE)
+public @interface ClientCriterion {
+    /**
+     * @return the client side counterpart for the annotated criterion
+     */
+    Class<? extends VAcceptCriteria> value();
+}
diff --git a/src/com/vaadin/event/dd/acceptCriteria/ComponentFilter.java b/src/com/vaadin/event/dd/acceptCriteria/ComponentFilter.java
index 85b0a953e3..fc0ffd2c53 100644
--- a/src/com/vaadin/event/dd/acceptCriteria/ComponentFilter.java
+++ b/src/com/vaadin/event/dd/acceptCriteria/ComponentFilter.java
@@ -7,8 +7,10 @@ import com.vaadin.event.ComponentTransferable;
 import com.vaadin.event.dd.DragAndDropEvent;
 import com.vaadin.terminal.PaintException;
 import com.vaadin.terminal.PaintTarget;
+import com.vaadin.terminal.gwt.client.ui.dd.VComponentFilter;
 import com.vaadin.ui.Component;
 
+@ClientCriterion(VComponentFilter.class)
 public class ComponentFilter extends ClientSideCriterion {
     private Component[] component;
 
diff --git a/src/com/vaadin/event/dd/acceptCriteria/IsDatabound.java b/src/com/vaadin/event/dd/acceptCriteria/IsDatabound.java
index 4b40296e3b..10ac493bf3 100644
--- a/src/com/vaadin/event/dd/acceptCriteria/IsDatabound.java
+++ b/src/com/vaadin/event/dd/acceptCriteria/IsDatabound.java
@@ -5,7 +5,9 @@ package com.vaadin.event.dd.acceptCriteria;
 
 import com.vaadin.event.DataBoundTransferable;
 import com.vaadin.event.dd.DragAndDropEvent;
+import com.vaadin.terminal.gwt.client.ui.dd.VDataBound;
 
+@ClientCriterion(VDataBound.class)
 public final class IsDatabound extends ClientSideCriterion {
     private static IsDatabound singleton = new IsDatabound();
 
diff --git a/src/com/vaadin/event/dd/acceptCriteria/Not.java b/src/com/vaadin/event/dd/acceptCriteria/Not.java
index 58d1aed5df..d11df81d55 100644
--- a/src/com/vaadin/event/dd/acceptCriteria/Not.java
+++ b/src/com/vaadin/event/dd/acceptCriteria/Not.java
@@ -4,7 +4,9 @@
 package com.vaadin.event.dd.acceptCriteria;
 
 import com.vaadin.event.dd.DragAndDropEvent;
+import com.vaadin.terminal.gwt.client.ui.dd.VNot;
 
+@ClientCriterion(VNot.class)
 public class Not extends ClientSideCriterion {
 
     private AcceptCriterion acceptCriterion;
diff --git a/src/com/vaadin/event/dd/acceptCriteria/Or.java b/src/com/vaadin/event/dd/acceptCriteria/Or.java
index 59f4de90f2..60b7152338 100644
--- a/src/com/vaadin/event/dd/acceptCriteria/Or.java
+++ b/src/com/vaadin/event/dd/acceptCriteria/Or.java
@@ -6,11 +6,13 @@ package com.vaadin.event.dd.acceptCriteria;
 import com.vaadin.event.dd.DragAndDropEvent;
 import com.vaadin.terminal.PaintException;
 import com.vaadin.terminal.PaintTarget;
+import com.vaadin.terminal.gwt.client.ui.dd.VOr;
 
 /**
  * TODO consider replacing this with intersection
  * 
  */
+@ClientCriterion(VOr.class)
 public class Or extends ClientSideCriterion {
     /**
      * 
diff --git a/src/com/vaadin/event/dd/acceptCriteria/OverTreeNode.java b/src/com/vaadin/event/dd/acceptCriteria/OverTreeNode.java
index 80321ef963..9eeed0b617 100644
--- a/src/com/vaadin/event/dd/acceptCriteria/OverTreeNode.java
+++ b/src/com/vaadin/event/dd/acceptCriteria/OverTreeNode.java
@@ -4,6 +4,7 @@
 package com.vaadin.event.dd.acceptCriteria;
 
 import com.vaadin.event.dd.DragAndDropEvent;
+import com.vaadin.terminal.gwt.client.ui.dd.VOverTreeNode;
 import com.vaadin.ui.Tree;
 import com.vaadin.ui.Tree.Location;
 import com.vaadin.ui.Tree.TreeDropDetails;
@@ -14,6 +15,7 @@ import com.vaadin.ui.Tree.TreeDropDetails;
  * TODO relocate close to {@link Tree} as this is tree specifif
  * 
  */
+@ClientCriterion(VOverTreeNode.class)
 public class OverTreeNode extends ClientSideCriterion {
 
     private static final long serialVersionUID = 1L;
diff --git a/src/com/vaadin/event/dd/acceptCriteria/ServerSideCriterion.java b/src/com/vaadin/event/dd/acceptCriteria/ServerSideCriterion.java
index 36a25346ca..382af29237 100644
--- a/src/com/vaadin/event/dd/acceptCriteria/ServerSideCriterion.java
+++ b/src/com/vaadin/event/dd/acceptCriteria/ServerSideCriterion.java
@@ -4,7 +4,9 @@ import java.io.Serializable;
 
 import com.vaadin.terminal.PaintException;
 import com.vaadin.terminal.PaintTarget;
+import com.vaadin.terminal.gwt.client.ui.dd.VServerAccept;
 
+@ClientCriterion(VServerAccept.class)
 public abstract class ServerSideCriterion implements Serializable,
         AcceptCriterion {
 
diff --git a/src/com/vaadin/terminal/gwt/client/ui/dd/ServerCriterion.java b/src/com/vaadin/terminal/gwt/client/ui/dd/ServerCriterion.java
deleted file mode 100644
index 3aca021146..0000000000
--- a/src/com/vaadin/terminal/gwt/client/ui/dd/ServerCriterion.java
+++ /dev/null
@@ -1,18 +0,0 @@
-package com.vaadin.terminal.gwt.client.ui.dd;
-
-import java.lang.annotation.ElementType;
-import java.lang.annotation.Retention;
-import java.lang.annotation.RetentionPolicy;
-import java.lang.annotation.Target;
-
-@Retention(RetentionPolicy.RUNTIME)
-@Target(ElementType.TYPE)
-public @interface ServerCriterion {
-    /**
-     * Class type would be nice but annotating should come from different
-     * direction to cope with gwt compiler.
-     * 
-     * @return
-     */
-    String value();
-}
diff --git a/src/com/vaadin/terminal/gwt/client/ui/dd/VAbstractDropHandler.java b/src/com/vaadin/terminal/gwt/client/ui/dd/VAbstractDropHandler.java
index aaf90f899d..2bf363d1ff 100644
--- a/src/com/vaadin/terminal/gwt/client/ui/dd/VAbstractDropHandler.java
+++ b/src/com/vaadin/terminal/gwt/client/ui/dd/VAbstractDropHandler.java
@@ -12,7 +12,7 @@ import com.vaadin.terminal.gwt.client.UIDL;
 public abstract class VAbstractDropHandler implements VDropHandler {
 
     private UIDL criterioUIDL;
-    private VAcceptCriteria acceptCriteria = new AcceptAll();
+    private VAcceptCriteria acceptCriteria = new VAcceptAll();
 
     /**
      * Implementor/user of {@link VAbstractDropHandler} must pass the UIDL
diff --git a/src/com/vaadin/terminal/gwt/client/ui/dd/AcceptAll.java b/src/com/vaadin/terminal/gwt/client/ui/dd/VAcceptAll.java
index 8600fe9fd5..2a5f993492 100644
--- a/src/com/vaadin/terminal/gwt/client/ui/dd/AcceptAll.java
+++ b/src/com/vaadin/terminal/gwt/client/ui/dd/VAcceptAll.java
@@ -5,8 +5,7 @@ package com.vaadin.terminal.gwt.client.ui.dd;
 
 import com.vaadin.terminal.gwt.client.UIDL;
 
-@ServerCriterion("com.vaadin.event.dd.acceptCriteria.AcceptAll")
-final class AcceptAll implements VAcceptCriteria {
+final public class VAcceptAll implements VAcceptCriteria {
     public void accept(VDragEvent drag, UIDL configuration,
             VAcceptCallback callback) {
         callback.accepted(drag);
diff --git a/src/com/vaadin/terminal/gwt/client/ui/dd/And.java b/src/com/vaadin/terminal/gwt/client/ui/dd/VAnd.java
index 42a341d7e3..42b77e2db3 100644
--- a/src/com/vaadin/terminal/gwt/client/ui/dd/And.java
+++ b/src/com/vaadin/terminal/gwt/client/ui/dd/VAnd.java
@@ -6,8 +6,7 @@ package com.vaadin.terminal.gwt.client.ui.dd;
 import com.vaadin.terminal.gwt.client.ApplicationConnection;
 import com.vaadin.terminal.gwt.client.UIDL;
 
-@ServerCriterion("com.vaadin.event.dd.acceptCriteria.And")
-final class And implements VAcceptCriteria {
+final public class VAnd implements VAcceptCriteria {
     private boolean b1;
     private boolean b2;
     private VAcceptCriteria crit1;
diff --git a/src/com/vaadin/terminal/gwt/client/ui/dd/ComponentCriteria.java b/src/com/vaadin/terminal/gwt/client/ui/dd/VComponentFilter.java
index ae129365c4..ce84d7aaab 100644
--- a/src/com/vaadin/terminal/gwt/client/ui/dd/ComponentCriteria.java
+++ b/src/com/vaadin/terminal/gwt/client/ui/dd/VComponentFilter.java
@@ -6,8 +6,7 @@ package com.vaadin.terminal.gwt.client.ui.dd;
 import com.vaadin.terminal.gwt.client.Paintable;
 import com.vaadin.terminal.gwt.client.UIDL;
 
-@ServerCriterion("com.vaadin.event.dd.acceptCriteria.ComponentFilter")
-final class ComponentCriteria implements VAcceptCriteria {
+final public class VComponentFilter implements VAcceptCriteria {
     public void accept(VDragEvent drag, UIDL configuration,
             VAcceptCallback callback) {
         try {
diff --git a/src/com/vaadin/terminal/gwt/client/ui/dd/HasItemId.java b/src/com/vaadin/terminal/gwt/client/ui/dd/VDataBound.java
index 30716b43a5..a5cfda3815 100644
--- a/src/com/vaadin/terminal/gwt/client/ui/dd/HasItemId.java
+++ b/src/com/vaadin/terminal/gwt/client/ui/dd/VDataBound.java
@@ -5,8 +5,7 @@ package com.vaadin.terminal.gwt.client.ui.dd;
 
 import com.vaadin.terminal.gwt.client.UIDL;
 
-@ServerCriterion("com.vaadin.event.dd.acceptCriteria.IsDatabound")
-final class HasItemId implements VAcceptCriteria {
+final public class VDataBound implements VAcceptCriteria {
     public void accept(VDragEvent drag, UIDL configuration,
             VAcceptCallback callback) {
         if (drag.getTransferable().getData("itemId") != null) {
diff --git a/src/com/vaadin/terminal/gwt/client/ui/dd/LazyInitItemIdentifiers.java b/src/com/vaadin/terminal/gwt/client/ui/dd/VLazyInitItemIdentifiers.java
index b1fed80336..689ed0eb62 100644
--- a/src/com/vaadin/terminal/gwt/client/ui/dd/LazyInitItemIdentifiers.java
+++ b/src/com/vaadin/terminal/gwt/client/ui/dd/VLazyInitItemIdentifiers.java
@@ -7,8 +7,12 @@ import java.util.HashSet;
 
 import com.vaadin.terminal.gwt.client.UIDL;
 
-@ServerCriterion("com.vaadin.ui.Tree.TreeDropCriterion")
-final class LazyInitItemIdentifiers implements VAcceptCriteria {
+/**
+ * 
+ * @deprecated example class testing custom behavior
+ */
+@Deprecated
+final public class VLazyInitItemIdentifiers implements VAcceptCriteria {
     private boolean loaded = false;
     private HashSet<String> hashSet;
     private VDragEvent lastDragEvent;
diff --git a/src/com/vaadin/terminal/gwt/client/ui/dd/Not.java b/src/com/vaadin/terminal/gwt/client/ui/dd/VNot.java
index 3b5915c73b..8ce753e886 100644
--- a/src/com/vaadin/terminal/gwt/client/ui/dd/Not.java
+++ b/src/com/vaadin/terminal/gwt/client/ui/dd/VNot.java
@@ -6,8 +6,7 @@ package com.vaadin.terminal.gwt.client.ui.dd;
 import com.vaadin.terminal.gwt.client.ApplicationConnection;
 import com.vaadin.terminal.gwt.client.UIDL;
 
-@ServerCriterion("com.vaadin.event.dd.acceptCriteria.Or")
-final class Not implements VAcceptCriteria {
+final public class VNot implements VAcceptCriteria {
     private boolean b1;
     private VAcceptCriteria crit1;
 
diff --git a/src/com/vaadin/terminal/gwt/client/ui/dd/Or.java b/src/com/vaadin/terminal/gwt/client/ui/dd/VOr.java
index ea79edcd4e..324dc08d6a 100644
--- a/src/com/vaadin/terminal/gwt/client/ui/dd/Or.java
+++ b/src/com/vaadin/terminal/gwt/client/ui/dd/VOr.java
@@ -6,8 +6,7 @@ package com.vaadin.terminal.gwt.client.ui.dd;
 import com.vaadin.terminal.gwt.client.ApplicationConnection;
 import com.vaadin.terminal.gwt.client.UIDL;
 
-@ServerCriterion("com.vaadin.event.dd.acceptCriteria.Or")
-final class Or implements VAcceptCriteria {
+final public class VOr implements VAcceptCriteria {
     private boolean b1;
     private boolean b2;
     private VAcceptCriteria crit1;
diff --git a/src/com/vaadin/terminal/gwt/client/ui/dd/OverTreeNode.java b/src/com/vaadin/terminal/gwt/client/ui/dd/VOverTreeNode.java
index 4948a31436..ebdc6bfed9 100644
--- a/src/com/vaadin/terminal/gwt/client/ui/dd/OverTreeNode.java
+++ b/src/com/vaadin/terminal/gwt/client/ui/dd/VOverTreeNode.java
@@ -5,8 +5,7 @@ package com.vaadin.terminal.gwt.client.ui.dd;
 
 import com.vaadin.terminal.gwt.client.UIDL;
 
-@ServerCriterion("com.vaadin.event.dd.acceptCriteria.OverTreeNode")
-final class OverTreeNode implements VAcceptCriteria {
+final public class VOverTreeNode implements VAcceptCriteria {
     public void accept(VDragEvent drag, UIDL configuration,
             VAcceptCallback callback) {
         Boolean containsKey = (Boolean) drag.getDropDetails().get(
diff --git a/src/com/vaadin/terminal/gwt/client/ui/dd/ServerAccept.java b/src/com/vaadin/terminal/gwt/client/ui/dd/VServerAccept.java
index 4cacfc1f4f..238b0c8cb4 100644
--- a/src/com/vaadin/terminal/gwt/client/ui/dd/ServerAccept.java
+++ b/src/com/vaadin/terminal/gwt/client/ui/dd/VServerAccept.java
@@ -5,8 +5,7 @@ package com.vaadin.terminal.gwt.client.ui.dd;
 
 import com.vaadin.terminal.gwt.client.UIDL;
 
-@ServerCriterion("com.vaadin.event.dd.acceptCriteria.ServerSideCriterion")
-final class ServerAccept implements VAcceptCriteria {
+final public class VServerAccept implements VAcceptCriteria {
     public void accept(final VDragEvent drag, UIDL configuration,
             final VAcceptCallback callback) {
 
diff --git a/src/com/vaadin/terminal/gwt/widgetsetutils/AcceptCriterionGenerator.java b/src/com/vaadin/terminal/gwt/widgetsetutils/AcceptCriterionGenerator.java
index b0dca0da20..91c50f046b 100644
--- a/src/com/vaadin/terminal/gwt/widgetsetutils/AcceptCriterionGenerator.java
+++ b/src/com/vaadin/terminal/gwt/widgetsetutils/AcceptCriterionGenerator.java
@@ -3,7 +3,6 @@ package com.vaadin.terminal.gwt.widgetsetutils;
 import java.io.PrintWriter;
 import java.util.Collection;
 import java.util.Date;
-import java.util.LinkedList;
 
 import com.google.gwt.core.ext.Generator;
 import com.google.gwt.core.ext.GeneratorContext;
@@ -14,7 +13,9 @@ import com.google.gwt.core.ext.typeinfo.JClassType;
 import com.google.gwt.core.ext.typeinfo.TypeOracle;
 import com.google.gwt.user.rebind.ClassSourceFileComposerFactory;
 import com.google.gwt.user.rebind.SourceWriter;
-import com.vaadin.terminal.gwt.client.ui.dd.ServerCriterion;
+import com.vaadin.event.dd.acceptCriteria.AcceptCriterion;
+import com.vaadin.event.dd.acceptCriteria.ClientCriterion;
+import com.vaadin.terminal.gwt.client.ui.dd.VAcceptCriteria;
 import com.vaadin.ui.ClientWidget;
 
 /**
@@ -89,27 +90,6 @@ public class AcceptCriterionGenerator extends Generator {
 
     }
 
-    private Collection<JClassType> getAvailableCriteria(GeneratorContext context) {
-
-        Collection<JClassType> crits = new LinkedList<JClassType>();
-
-        JClassType[] types = context.getTypeOracle().getTypes();
-        for (int i = 0; i < types.length; i++) {
-            JClassType jClassType = types[i];
-            JClassType[] implementedInterfaces = jClassType
-                    .getImplementedInterfaces();
-            for (int j = 0; j < implementedInterfaces.length; j++) {
-                String qualifiedSourceName = implementedInterfaces[j]
-                        .getQualifiedSourceName();
-                if (qualifiedSourceName
-                        .equals("com.vaadin.terminal.gwt.client.ui.dd.VAcceptCriteria")) {
-                    crits.add(jClassType);
-                }
-            }
-        }
-        return crits;
-    }
-
     private void generateInstantiatorMethod(SourceWriter sourceWriter,
             GeneratorContext context, TreeLogger logger) {
 
@@ -118,30 +98,21 @@ public class AcceptCriterionGenerator extends Generator {
 
         sourceWriter.println("name = name.intern();");
 
-        Collection<JClassType> paintablesHavingWidgetAnnotation = getAvailableCriteria(context);
-
-        for (JClassType jClassType : paintablesHavingWidgetAnnotation) {
-            ServerCriterion annotation = jClassType
-                    .getAnnotation(ServerCriterion.class);
-            if (annotation == null) {
-                // throw new RuntimeException(
-                // "No server side implementation defined for "
-                // + jClassType.getName());
-                continue;
-            } else {
-                System.out.print("Printing for instantiation rule for "
-                        + annotation.value());
-            }
-            String serversideclass = annotation.value();
+        Collection<Class<? extends AcceptCriterion>> clientSideVerifiableCriterion = ClassPathExplorer
+                .getCriterion();
 
+        for (Class<? extends AcceptCriterion> class1 : clientSideVerifiableCriterion) {
+            String canonicalName = class1.getCanonicalName();
+            Class<? extends VAcceptCriteria> clientClass = class1
+                    .getAnnotation(ClientCriterion.class).value();
             sourceWriter.print("if (\"");
-            sourceWriter.print(serversideclass);
+            sourceWriter.print(canonicalName);
             sourceWriter.print("\" == name) return GWT.create(");
-            sourceWriter.print(jClassType.getName());
+            sourceWriter.print(clientClass.getCanonicalName());
             sourceWriter.println(".class );");
             sourceWriter.print("else ");
-
         }
+
         sourceWriter.println("return null;");
         sourceWriter.outdent();
         sourceWriter.println("}");
diff --git a/src/com/vaadin/terminal/gwt/widgetsetutils/ClassPathExplorer.java b/src/com/vaadin/terminal/gwt/widgetsetutils/ClassPathExplorer.java
index 912cfa37a3..b3c670ba81 100644
--- a/src/com/vaadin/terminal/gwt/widgetsetutils/ClassPathExplorer.java
+++ b/src/com/vaadin/terminal/gwt/widgetsetutils/ClassPathExplorer.java
@@ -27,6 +27,8 @@ import java.util.jar.Manifest;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
+import com.vaadin.event.dd.acceptCriteria.AcceptCriterion;
+import com.vaadin.event.dd.acceptCriteria.ClientCriterion;
 import com.vaadin.terminal.Paintable;
 import com.vaadin.ui.ClientWidget;
 
@@ -83,6 +85,15 @@ public class ClassPathExplorer {
 
     }
 
+    public static Collection<Class<? extends AcceptCriterion>> getCriterion() {
+        if (acceptCriterion.isEmpty()) {
+            // accept criterion are searched as a side effect, normally after
+            // paintable detection
+            getPaintablesHavingWidgetAnnotation();
+        }
+        return acceptCriterion;
+    }
+
     /**
      * Finds available widgetset names.
      * 
@@ -385,6 +396,8 @@ public class ClassPathExplorer {
         }
     });
 
+    private static Set<Class<? extends AcceptCriterion>> acceptCriterion = new HashSet<Class<? extends AcceptCriterion>>();
+
     private static void tryToAdd(final String fullclassName,
             Collection<Class<? extends Paintable>> paintables) {
         try {
@@ -401,7 +414,10 @@ public class ClassPathExplorer {
             if (c.getAnnotation(ClientWidget.class) != null) {
                 paintables.add((Class<? extends Paintable>) c);
                 // System.out.println("Found paintable " + fullclassName);
+            } else if (c.getAnnotation(ClientCriterion.class) != null) {
+                acceptCriterion.add((Class<? extends AcceptCriterion>) c);
             }
+
         } catch (ClassNotFoundException e) {
             // e.printStackTrace();
         } catch (LinkageError e) {
diff --git a/src/com/vaadin/ui/Tree.java b/src/com/vaadin/ui/Tree.java
index 3bb1e6f696..ab8eae8419 100644
--- a/src/com/vaadin/ui/Tree.java
+++ b/src/com/vaadin/ui/Tree.java
@@ -33,6 +33,7 @@ import com.vaadin.event.dd.DragSource;
 import com.vaadin.event.dd.DropHandler;
 import com.vaadin.event.dd.DropTarget;
 import com.vaadin.event.dd.TargetDetailsImpl;
+import com.vaadin.event.dd.acceptCriteria.ClientCriterion;
 import com.vaadin.event.dd.acceptCriteria.ServerSideCriterion;
 import com.vaadin.terminal.KeyMapper;
 import com.vaadin.terminal.PaintException;
@@ -40,6 +41,7 @@ import com.vaadin.terminal.PaintTarget;
 import com.vaadin.terminal.Resource;
 import com.vaadin.terminal.gwt.client.MouseEventDetails;
 import com.vaadin.terminal.gwt.client.ui.VTree;
+import com.vaadin.terminal.gwt.client.ui.dd.VLazyInitItemIdentifiers;
 
 /**
  * Tree component. A Tree can be used to select an item (or multiple items) from
@@ -1218,6 +1220,7 @@ public class Tree extends AbstractSelect implements Container.Hierarchical,
      * <p>
      * See client side counterpart
      */
+    @ClientCriterion(VLazyInitItemIdentifiers.class)
     public static abstract class TreeDropCriterion extends ServerSideCriterion {
 
         private Tree tree;