public static H2AsyncClientBuilder create() {
        return new H2AsyncClientBuilder();
    }
Builder for HTTP/2 only {@link CloseableHttpAsyncClient} instances.
<p>
Concurrent message exchanges with the same connection route executed
with these {@link CloseableHttpAsyncClient} instances will get
automatically multiplexed over a single physical HTTP/2 connection.
</p>
<p>
When a particular component is not explicitly set this class will
use its default implementation.
<p>

@since 5.0
httpclient5/src/main/java/org/apache/hc/client5/http/impl/async/H2AsyncClientBuilder.java