should I run nodejs in http2 when nginx is host http2

Question

I was running Web App on NodeJS v8.4 to try http2.
I run some test and found out some interesting result.
Here is three test scenario:

1. nginx listen 443 ssl http2 <--> redirect to nodejs run http2
2. nginx listen 443 ssl http2 <--> redirect to nodejs run http
3. nginx listen 443 ssl <--> redirect to nodejs run http

I open chrome dev tool to check which protocol is used when loading resources.
The result is first two methods all run in http2 and Waterfall is almost the same.
The last one is run in http1.1 and the waterfall is as expected

I wana make sure if I need to run NodeJS in http2 when nginx is host in http2