@Override protected void configure(ServerBuilder sb) {
      sb.service("/", (ctx, req) -> sendResponseAfterAggregate(req, VERSION_RESPONSE));
      sb.service("/_cluster/health", HealthCheckService.of(server2Health));
      sb.serviceUnder("/_cluster/health/",
        (ctx, req) -> sendResponseAfterAggregate(req, GREEN_RESPONSE));
    }
This ensures the response is sent after the request is fully read.
zipkin-server/src/test/java/zipkin2/server/internal/elasticsearch/ITElasticsearchHealthCheck.java