@UnstableApi
    public static ArmeriaRetrofitBuilder builder(HttpPreprocessor httpPreprocessor, String path) {
        return builder(WebClient.of(httpPreprocessor, path));
    }
Returns a new {@link ArmeriaRetrofitBuilder} which is configured with specified {@link HttpPreprocessor}
and {@code path}.
retrofit2/src/main/java/com/linecorp/armeria/client/retrofit2/ArmeriaRetrofit.java