@Get("/api/v2/remoteServices")
  @Blocking
  public AggregatedHttpResponse getRemoteServiceNames(
    @Param("serviceName") String serviceName, ServiceRequestContext ctx)
    throws IOException {
    List<String> remoteServiceNames =
      storage.serviceAndSpanNames().getRemoteServiceNames(serviceName).execute();
    return maybeCacheNames(serviceCount > 3, remoteServiceNames, 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