TreeGrid Drag & Drop Error

[doit]

Hi,
when I'm trying to do a drag&drop operation from a ListGrid to a TreeGrid I'm getting the following error (SmartGWT 2.5 various nightly builds):

IDE Console:

ERROR: 08:52:27.341:MUP7:WARN:Log:Attempt to add properties to a null object. Creating a new object for the list of properties.. com.smartgwt.client.core.JsObject$SGWT_WARN: 08:52:27.341:MUP7:WARN:Log:Attempt to add properties to a null object. Creating a new object for the list of properties.
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
	at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:105)
	at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
	at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:157)
	at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessages(BrowserChannelServer.java:281)
	at com.google.gwt.dev.shell.BrowserChannelServer.processConnection(BrowserChannelServer.java:531)
	at com.google.gwt.dev.shell.BrowserChannelServer.run(BrowserChannelServer.java:352)
	at java.lang.Thread.run(Thread.java:662)

Developer Console:

08:43:47.472:MDN7:INFO:dragDrop:target is draggable with dragOperation: drag, dragTarget is :[ListGrid ID:isc_ListGrid_0] (delegated from: [GridBody ID:isc_ListGrid_0_body])
08:43:47.565:TMR6:INFO:dragDrop:Started dragOperation: drag with dragTarget:[ListGrid ID:isc_ListGrid_0] dragAppearance: tracker
08:43:47.583:TMR0:DEBUG:dragDrop:New drop target: [TreeGridBody ID:isc_TreeGrid_0_body]
08:43:48.460:MUP2:INFO:dragDrop:end of drag interaction
[b]08:43:48.534:MUP2:WARN:Log:Attempt to add properties to a null object. Creating a new object for the list of properties.[/b]
08:43:48.548:MUP2:DEBUG:dragDrop:Invoking transferDragData from inside transferNodes - no server queries needed?
08:43:48.584:XRP8:DEBUG:dragDrop:Decrementing update count - was 1
08:43:48.591:XRP8:DEBUG:dragDrop:All updates complete, calling dragComplete()

The operation seems to work properly though. I was just wondering what causes this error and how I can get rid of it.

My code looks like:

EntryPoint

    public void onModuleLoad() {
        HLayout hLayout = new HLayout();
        hLayout.setWidth100();
        hLayout.setHeight100();
        TreeGrid tree = new TreeGrid();
        tree.setDataSource(DataSource.get("treeEntityDS"));
        tree.setAutoFetchData(true);
        tree.setCanAcceptDroppedRecords(true);
        tree.addFolderDropHandler(new FolderDropHandler() {
            public void onFolderDrop(FolderDropEvent event) {
                // omitted
            }
        });

        hLayout.addMember(tree);

        ListGrid list = new ListGrid();
        list.setDataSource(DataSource.get("listEntityDS"));
        list.setAutoFetchData(true);
        list.setCanDragRecordsOut(true);
        list.setDragDataAction(DragDataAction.COPY);

        hLayout.addMember(list);

        hLayout.draw();
    }

ListEntity

@Entity
public class ListEntity {

    private Long id;
    private String name;

    @Id
    @GeneratedValue
    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

TreeEntity

@Entity
public class TreeEntity {

    private Long id;
    private TreeEntity parent;
    private Long parentId;

    @Id
    @GeneratedValue
    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    @ManyToOne
    @JoinColumn(name = "parentId", referencedColumnName = "id", insertable = false, updatable = false)
    public TreeEntity getParent() {
        return parent;
    }

    public void setParent(TreeEntity parent) {
        this.parent = parent;
    }

    public Long getParentId() {
        return parentId;
    }

    public void setParentId(Long parentId) {
        this.parentId = parentId;
    }
}

listEntityDS

<DataSource ID="listEntityDS" serverConstructor="com.isomorphic.jpa.JPADataSource"
            beanClassName="de.doitnetworks.server.entity.ListEntity">
    <fields>
        <field name="id" type="integer" hidden="true" primaryKey="true"/>
        <field name="name" title="Name" type="text" required="true" canEdit="true"/>
    </fields>

    <serverObject lookupStyle="new" className="sample.server.dmi.ListEntityDmi"/>
</DataSource>

treeEntityDS

<DataSource ID="treeEntityDS" serverConstructor="com.isomorphic.jpa.JPADataSource"
            beanClassName="de.doitnetworks.server.entity.TreeEntity">
    <fields>
        <field name="id" type="integer" hidden="true" primaryKey="true"/>
        <field name="parentId" type="integer" foreignKey="treeEntityDS.id" required="false"
               hidden="true"/>
    </fields>

    <serverObject lookupStyle="new" className="sample.server.dmi.TreeEntityDmi"/>
</DataSource>

The ListEntity should be converted to a TreeEntity by setting some attributes in the folderDropHandler+handling on the server side, but I omitted that because it makes no difference.

[Isomorphic]

Several fixes were made in this area earlier in the week, please retest with the latest nightly..

If that doesn't fix your problem, please show a test-case.

[doit]

It really seems to work with the latest nightly build from 2011-06-09.
It didn't work with 2011-06-07.

Thanks for the fast reply.