JSON Batch: clarify values of body property, context URL, batch in batch, continue-on-error

From 2019-6-6 discussion: Responses for all except #3 seem straightforward. We'll open a separate issue for #3. The rest are as proposed: Yes, "body":null and omitting the body property both mean "no body" Yes, "body":null 3. issue ODATA-1309 created to track this issue. 4. body content can be compressed/chunked if correctly reflected in Transfer-Encoding header 5. explicitly mention that these don't have a context URL 6. Part 1: Protocol clearly defines which requests can be inside a batch request, and batch is not listed: Batch requests allow grouping multiple individual requests into a single HTTP request payload. An individual request in the context of a batch request is a Metadata Request , Data Request , Data Modification Request , Action invocation request, or Function invocation request. 7. If processing stops on error the batch response can be incomplete, whereas with dependsOn the batch response would contain a response for each individual request which has status:412 if the request has been skipped due to a failed dependency