draft-ietf-httpbis-h2-websockets-03

5.  Using Extended CONNECT To Bootstrap The WebSocket Protocol
https://tools.ietf.org/html/draft-ietf-httpbis-h2-websockets-03#section-5

|   [RFC6455] requires the use of a Host header which is also not part of
|   HTTP/2.  The Host information is conveyed as part of the :authority
|   pseudo-header which is required on every HTTP/2 transaction.


RFC 7540

8.1.2.3.  Request Pseudo-Header Fields
https://tools.ietf.org/html/rfc7540#section-8.1.2.3

requirements is little more complex:

|      To ensure that the HTTP/1.1 request line can be reproduced
|      accurately, this pseudo-header field MUST be omitted when
|      translating from an HTTP/1.1 request that has a request target in
|      origin or asterisk form (see [RFC7230], Section 5.3).  Clients
|      that generate HTTP/2 requests directly SHOULD use the ":authority"
|      pseudo-header field instead of the Host header field.  An
|      intermediary that converts an HTTP/2 request to HTTP/1.1 MUST
|      create a Host header field if one is not present in a request by
|      copying the value of the ":authority" pseudo-header field.


Regurement if :authority is just "SHOULD". So it is NOT
required on every HTTP/2 transaction. That also can be Host
header instead.

/ Kari Hurtta