CallThingie.java

public class HttpClient implements Call.Factory {

    private final OkHttpClient ok;

    HttpClient(final OkHttpClient ok) {
        this.ok = ok;
    }

    /**
     * Returns a CompletableCall, which supports CompletableFuture based enqueueing.
     */
    public CompletableCall newCall(final Request request) {
        return newCall(Ctx.fromThread().orElseGet(Ctx::empty), request);
    }

    /**
     * Returns a CompletableCall, which supports CompletableFuture based enqueueing
     */
    public CompletableCall newCall(Ctx ctx, final Request request) {
        OkHttpClient.Builder b = this.ok.newBuilder();
        b.interceptors().add(0, new CtxInterceptor(ctx));
        return new CompletableCall(ctx, b.build().newCall(request));
    }