FileUpload in GAE is unable to update UI from Finishhandler/ Successhandler

Hi,

I am using vaadin 7.2.1 on Google Application Engine. I have notcied upload component is unable to update UI after sucess/finish event.

I am able to receive file and save to datastore. But I am unable to notify UI/ update ui with uploaded image. I have tried setting component markasdirty().