Try to use HTTP pipelining while communicating with the backend REST API

[jelkosz]

No description provided.

[atiratree]

We would have to change the implementation of our REST Client (org.springframework.web.client.RestTemplate) to support this, because it doesn't seem to implement pipelining.

I looked at OkHtttp and other popular clients and they also don't seem to implement it (square/okhttp#1893).

One possibility is to use netty or something built on it (https://github.com/typesafehub/netty-http-pipelining).