@UnstableApi
    public boolean preferHttp1() {
        return get(PREFER_HTTP1);
    }
Returns whether to use HTTP/1.1 instead of HTTP/2 . If {@code true}, the client will not attempt to
upgrade to HTTP/2 for {@link SessionProtocol#HTTP} and {@link SessionProtocol#HTTPS}.
core/src/main/java/com/linecorp/armeria/client/ClientFactoryOptions.java