@Override
    AsyncExecRuntime createAsyncExecRuntime(final HandlerFactory<AsyncPushConsumer> pushHandlerFactory) {
        return new InternalHttpAsyncExecRuntime(LOG, manager, getConnectionInitiator(), pushHandlerFactory, tlsConfig);
    }
Internal implementation of {@link CloseableHttpAsyncClient} that can negotiate
the most optimal HTTP protocol version during during the {@code TLS} handshake
with {@code ALPN} extension if supported by the Java runtime.
<p>
Concurrent message exchanges executed by this client will get assigned to
separate connections leased from the connection pool.
</p>

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