public static ClientBuilder builder(Scheme scheme, EndpointGroup endpointGroup) {
        requireNonNull(scheme, "scheme");
        requireNonNull(endpointGroup, "endpointGroup");
        return new ClientBuilder(scheme, endpointGroup, null);
    }
Returns a new {@link ClientBuilder} that builds the client that connects to the specified
{@link EndpointGroup} with the specified {@link Scheme}.
core/src/main/java/com/linecorp/armeria/client/Clients.java