Are the following reasonable interpretations of the spec?
* It would appear that since FederationRequestData is per batchRequest item, different searchRequests in the same batchRequest could have different federation settings.
* It looks like in the federated case, SearchResponses would have the union of SearchResultEntry items of the federated results, rather than having multiple SearchRespons elements with the same requestId. This would appear to be required per the DSMLv2 spec section 4, heading "Request-response association". Likewise, if the downstream HPD is federated, then FederatedSearchResponseData would need to be merged such that it's list of federatedResponseStatus would contain the union of the downstream FSRDs received/generated.