public static CloseableHttpAsyncClient createHttp2System() {
        return H2AsyncClientBuilder.create().useSystemProperties().build();
    }
Creates HTTP/2 {@link CloseableHttpAsyncClient} instance with default configuration and
system properties optimized for HTTP/2 protocol and message multiplexing.
httpclient5/src/main/java/org/apache/hc/client5/http/impl/async/HttpAsyncClients.java