SyncStack - Investigate usage of BinaryData as HttpRequest body carrier.

[kasobol-msft]

The HttpRequest uses Flux<ByteBuffer> to carry body from upper layers to the HttpClient. Consider changing that carrier to something that defers assumption of what's really backing the payload (whether it's stream, buffer, byte[] or flux) until absolutely necessary.
For example today binary payloads are eagerly converted to flux in convenience layers - and then often converted to something else at http client layer (apart from reactor-netty that speaks flux). If somebody is providing InputStream as upload data source then the decision how to use that should be up to http client how best consume that payload.

Known challenges:

• RestProxy - how do we validate length for different BinaryDataContent types?
• RetryPolicy - This is tightly coupled to Flux operators. How do we retry?
• Should we generalize beyond BinaryData ?
• How do we leverage each http client's consumption options to minimize transformations?
• How do we leverage seekability of files or in memory buffers to remove body buffering for some scenarios?

The usage of HttpRequest.body is widespread. Those more difficult usage patterns (like RetryPolicy) might be deferred (i.e. conversion to flux) and a work item to cover that created. The priority should be to cover sync/async RestProxy logic first.

[kasobol-msft]

#28737

[kasobol-msft]

#28829

[kasobol-msft]

#29084

#28889