public static Function<? super RpcService, BraveRpcService>
    newDecorator(RpcTracing rpcTracing) {
        ensureScopeUsesRequestContext(rpcTracing.tracing());
        return service -> new BraveRpcService(service, rpcTracing);
    }
Creates a new tracing {@link RpcService} decorator using the specified {@link RpcTracing} instance.
brave/brave6/src/main/java/com/linecorp/armeria/server/brave/BraveRpcService.java