I am creating a custom connector for our DAM system and am having an issue where I get many exceptions being thrown of the following form:

2012/02/08 08:50:31,145 [ConnectionHandler-kernel] ERROR NCommDelegate - Caught exception

java.lang.AssertionError: version != null

          at com.adobe.drive.internal.data.manager.DataManager.getVersionProperty( DataManager.java:5925)

          at com.adobe.drive.internal.biz.filesystem.XAttrManager.getXAttr(XAttrMa nager.java:120)

          at com.adobe.drive.internal.biz.filesystem.FileSystemService.createStatI nfoEx(FileSystemService.java:1410)

          at com.adobe.drive.internal.biz.filesystem.FileSystemService.access$500( FileSystemService.java:102)

          at com.adobe.drive.internal.biz.filesystem.FileSystemService$5.execute(F ileSystemService.java:492)

          at com.adobe.drive.internal.biz.filesystem.FileSystemService$5.execute(F ileSystemService.java:452)

          at com.adobe.drive.internal.biz.filesystem.FileSystemService$FSCallable. run(FileSystemService.java:1789)

          at com.adobe.drive.data.internal.persistence.PersistenceRunner$2.runWith Transaction(PersistenceRunner.java:186)

          at com.adobe.drive.data.internal.persistence.PersistenceModificationCall able.run(PersistenceModificationCallable.java:71)

          at com.adobe.drive.data.internal.persistence.PersistenceRunner.run(Persi stenceRunner.java:119)

          at com.adobe.drive.data.internal.persistence.PersistenceRunner.runWithTr ansaction(PersistenceRunner.java:181)

          at com.adobe.drive.internal.biz.filesystem.FileSystemService.runWithTran saction(FileSystemService.java:1744)

          at com.adobe.drive.internal.biz.filesystem.FileSystemService.lookup(File SystemService.java:451)

          at com.adobe.drive.internal.ncomm.filesystem.StatHandler.handleRequest(S tatHandler.java:72)

          at com.adobe.drive.internal.ncomm.filesystem.AbstractHandler$1.call(Abst ractHandler.java:204)

          at com.adobe.drive.model.context.Context.run(Context.java:88)

          at com.adobe.drive.internal.ncomm.filesystem.AbstractHandler.handleWithC ontext(AbstractHandler.java:200)

          at com.adobe.drive.internal.ncomm.filesystem.AbstractHandler.handle(Abst ractHandler.java:66)

          at com.adobe.csi.internal.ncomm.NCommDelegate.execute(NCommDelegate.java :107)

          at com.adobe.versioncue.internal.nativecomm.host.Host.execute(Host.java: 200)

          at com.adobe.versioncue.internal.nativecomm.host.ConnectionHandler.handl eRequest(ConnectionHandler.java:162)

          at com.adobe.versioncue.internal.nativecomm.host.ConnectionHandler.run(C onnectionHandler.java:81)

          at java.lang.Thread.run(Thread.java:680)

This is during simple browse operations - I select "Open in Finder" from Adobe Drive and then many calls to GetAssetsHandler are made (in which I am doing appropriate createFileUpdateRecipe() / createFielContainerUpdateRecipe() plus createBasicData() for each container and asset.  All of my assets do have a version number set.  It looks like some open / read operations are also happening right before these exceptions.  If I ignore the exceptions, I am actually able to do some basic browsing of my DAM, even getting previews of JPEG files in finder (so I think the open and read are working).  I just don't know what these version exceptions are being caused by.

I'm trying to follow the general flow that the FTP sample connector uses, but am a bit stumped. 

Thanks very much in advance.