/**
* {@inheritDoc}
*/
public ShardRequest[] constructRequest(ResponseBuilder rb) {
ShardRequest sreq = new ShardRequest();
GroupingSpecification groupingSpecification = rb.getGroupingSpec();
if (groupingSpecification.getFields().length == 0) {
return new ShardRequest[0];
}
sreq.purpose = ShardRequest.PURPOSE_GET_TOP_GROUPS;