@Get("/api/v2/services")
    @Blocking
    public AggregatedHttpResponse getServiceNames() throws IOException {
        List<String> serviceNames = getZipkinQueryDAO().getServiceNames();
        serviceCount = serviceNames.size();
       return cachedResponse(serviceCount > 3, serviceNames);
    }
Reference from zipkin2.server.internal.ZipkinQueryApiV2 for the API consistent.
oap-server/server-query-plugin/zipkin-query-plugin/src/main/java/org/apache/skywalking/oap/query/zipkin/handler/ZipkinQueryHandler.java