Motivation:
HttpClientUpgradeHandler uses HttpHeaderNames.UPGRADE as the value of
the 'Connection' header, which is incorrect. It should use
HttpHeaderValues.UPGRADE instead (note Names vs Values.)
Also, HttpHeaderValues.UPGRADE should be 'upgrade' rather than
'Upgrade', as defined in:
- https://tools.ietf.org/html/rfc7230#section-6.7
Modifications:
- Use HttpHeaderValues.UPGRADE for a 'Connection' header
- Lowercase the value of HttpHeaderValues.UPGRADE
Result:
- Fixes#4508
- Correct behavior
d68219c4e4