Problem with DataCommunicator in Vaadin 8.1.0beta2

Hi,

when I tried to upgrade from Vaadin 8.0.6 to Vaadin 8.1.0beta2, I ran into a problem with DataCommunicatior respectively (List)DataProvider.getId() and the Items of the actual List, which looks like this

List[0]
 = null
List[1]
 = true
List[2]
 = false

First of all, here’s stack trace:

java.lang.NullPointerException: Cannot provide an id for a null item.
    at java.util.Objects.requireNonNull(Objects.java:228)
    at com.vaadin.data.provider.DataProvider.getId(DataProvider.java:132)
    at com.vaadin.server.KeyMapper.refresh(KeyMapper.java:126)
    at com.vaadin.data.provider.DataCommunicator$ActiveDataHandler.generateData(DataCommunicator.java:170)
    at com.vaadin.data.provider.DataCommunicator.getDataObject(DataCommunicator.java:437)
    at com.vaadin.data.provider.DataCommunicator.pushData(DataCommunicator.java:417)
    at com.vaadin.data.provider.DataCommunicator.sendDataToClient(DataCommunicator.java:341)
    at com.vaadin.data.provider.DataCommunicator.beforeClientResponse(DataCommunicator.java:310)
    at com.vaadin.server.communication.UidlWriter.write(UidlWriter.java:126)
    at com.vaadin.server.communication.UidlRequestHandler.writeUidl(UidlRequestHandler.java:124)

The reason is obviously that DataProvider.getId(null) fails due to its check:

Objects.requireNonNull(item, "Cannot provide an id for a null item."); But is this really intended? As far as I can comprehend, getId on DataProvider didn’t really change from 8.0.6 to 8.1.0, but why is it called in 8.1.0 and not in 8.0.6?

Kind regards
Michael