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

Response name	Returned by	Strong-typed key?	Value type
BatchResponse	BatchGetRequestBuilder.build()	No	T
BatchKVResponse	BatchGetRequestBuilder.buildKV()	Yes	T
BatchEntityResponse	BatchGetEntityRequestBuilder.build()	Yes	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).