We're discussing this issue, but we can't commit on a resolution for the moment.
The HierarchicalDataSource is actually a "data source of data sources" of sorts.
This makes tasks such as filtering, calculating totals and so on quite tricky.
It's unclear how the total should be calculated when using virtualization for example.
In this case all data sources will share the same server endpoint. It's not trivial to return the right count from the server.
We're still not decided on what the best approach would be, but a short-term fix is unlikely at this point.
Apologies for the caused inconvenience.
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