@Override
                        public void completed(final AsyncExecRuntime execRuntime) {
                            if (execRuntime.isEndpointConnected()) {
                                try {
                                    chain.proceed(request, entityProducer, scope, asyncExecCallback);
                                } catch (final HttpException | IOException ex) {
                                    asyncExecCallback.failed(ex);
                                }
                            } else {
                                proceedToNextHop(state, request, entityProducer, scope, chain, asyncExecCallback);
                            }
                        }
Request execution handler in the asynchronous request execution chain
that is responsible for establishing connection to the target
origin server as specified by the current connection route.

@since 5.0
httpclient5/src/main/java/org/apache/hc/client5/http/impl/async/AsyncConnectExec.java