@Override protected void configure(ServerBuilder sb) {
      sb.service("/", (ctx, req) -> sendResponseAfterAggregate(req, VERSION_RESPONSE));
      sb.service("/_cluster/health", HealthCheckService.of(server1Health));
      sb.serviceUnder("/_cluster/health/", (ctx, req) -> GREEN_RESPONSE.toHttpResponse());
    }
These tests focus on http client health checks not currently in zipkin-storage-elasticsearch.
zipkin-server/src/test/java/zipkin2/server/internal/elasticsearch/ITElasticsearchHealthCheck.java