@Override
                        public AsyncDataConsumer handleResponse(
                                final HttpResponse backendResponse2,
                                final EntityDetails entityDetails1) throws HttpException, IOException {
                            final Instant responseDate2 = getCurrentDate();
                            final AsyncExecCallback callback2 = evaluateResponse(backendResponse2, responseDate2);
                            callbackRef.set(callback2);
                            return callback2.handleResponse(backendResponse2, entityDetails1);
                        }
Request executor in the request execution chain that is responsible for
transparent client-side caching.
<p>
The current implementation is conditionally
compliant with HTTP/1.1 (meaning all the MUST and MUST NOTs are obeyed),
although quite a lot, though not all, of the SHOULDs and SHOULD NOTs
are obeyed too.

@since 5.0
httpclient5-cache/src/main/java/org/apache/hc/client5/http/impl/cache/AsyncCachingExec.java