[Question] http, http2 instruments add RECEIVED MessageEvent at the end of response

[StoneDot]

I'd thought MessageEvent (MessageEventType.RECEIVED) is added at the start of a span. But current implementation of http and http2 instruments add the MessageEvent at the end of a span.
I feel it is curious behavior because the whole request has already received when request event is emitted.

Is this intended behavior?

• OpenCensus version: 0.0.16
• Node.js version: v11.11.0