@Get("/api/v2/autocompleteValues")
  @Blocking
  public AggregatedHttpResponse getAutocompleteValues(
    @Param("key") String key, ServiceRequestContext ctx) throws IOException {
    List<String> values = storage.autocompleteTags().getValues(key).execute();
    return maybeCacheNames(values.size() > 3, values, ctx.alloc());
  }
The Cache-Control max-age (seconds) for /api/v2/services /api/v2/remoteServices and
/api/v2/spans
zipkin-server/src/main/java/zipkin2/server/internal/ZipkinQueryApiV2.java