@Test void allHealthy() {
    try (ElasticsearchStorage storage = context.getBean(ElasticsearchStorage.class)) {

      // There's an initialization delay, so await instead of expect everything up now.
      awaitTimeout.untilAsserted(() -> assertThat(storage.check().ok()).isTrue());
    }
  }
This ensures the response is sent after the request is fully read.
zipkin-server/src/test/java/zipkin2/server/internal/elasticsearch/ITElasticsearchHealthCheck.java