Rest.li 2.0 response API

Pegasus 1.17.2 features a new set of response APIs for various batch operations. The motivation of this change is to simplify the old response APIs. This change focuses on two sets of operations: BatchGet and BatchUpdate/BatchPartialUpdate/BatchDelete.

BatchGet

Previously there are two variations of responses for BatchGet: BatchResponse and BatchKVResponse. BatchResponse is returned when the request is built by calling BatchGetRequestBuilder.build().BatchKVResponse is returned when the request is built by calling BatchGetRequestBuilder.buildKV(). The major difference between them is that BatchResponse provides the raw string form of key, while BatchKVResponse provides deserialized strong-typed key.

In 1.17.2, we introduce the third variation BatchEntityResponse, a specialized BatchKVResponse whose value is wrapped in a EntityResponse. EntityResponse contains three fields:

• entity provides an entity record if the server resource finds a corresponding value for the key;
• status provides an optional status code;
• error provides the error detail from the server resource (generally entity and error are mutually exclusive, but it is ultimately up to the server resource).