Issues with Datastore deleteBy methods

[Alos]

Describe the bug
Using Spring Cloud GCP 1.2.1.RELEASE the following method is not implemented:

 void deleteAlertByCreatedDateBefore(Instant createdDate);

Using this method produces the following error:

org.springframework.cloud.gcp.data.datastore.core.mapping.DatastoreDataException: Unsupported predicate keyword: BEFORE (1): [IsBefore, Before]

In addition:

void deleteByCreatedDateLessThan(Instant createdDate);

Works but it only deletes one entity from datastore. The following correctly removes all the entities that match the query:

int deleteByCreatedDateLessThan(Instant createdDate);

The returned int contains the count of the entities removed. I'm not quite sure if this is expected or we are just using it wrong.