private String getContentEncodingFromRequestThatAcceptsGzip(String path) {
    // We typically use OkHttp in our tests, but that automatically unzips..
    AggregatedHttpResponse response = WebClient.of(url(server, "/"))
      .execute(RequestHeaders.of(HttpMethod.GET, path, HttpHeaderNames.ACCEPT_ENCODING, "gzip"))
      .aggregate().join();

    return response.headers().get(HttpHeaderNames.CONTENT_ENCODING);
  }
index.html is served separately. This tests other content is also loaded from the classpath.
zipkin-server/src/test/java/zipkin2/server/internal/ui/ITZipkinUiConfiguration.java