As of today, the Datasource seems to be fully compatible with OData-v4, however, when server-side grouping and aggregation is enabled, we still need to provide a parametermap to correctly encode the group[] and group[aggregates[]] into the URL.

The OData specification should be followed and the URL build by the Datasource when the type is set to "odata-v4":

$apply=groupby((Field1, Field2))

or

$apply=grouppy((Field),aggregate($count as CountField))

thus saving the developers from providing their own encoding implementation.