void triggerCachedResponse(final HttpCacheEntry entry) {
            final HttpCacheContext context = HttpCacheContext.cast(scope.clientContext);
            try {
                final SimpleHttpResponse cacheResponse = responseGenerator.generateResponse(request, entry);
                context.setCacheEntry(entry);
                triggerResponse(cacheResponse, scope, asyncExecCallback);
            } catch (final ResourceIOException ex) {
                asyncExecCallback.failed(ex);
            }
        }
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