header.go
func (h *RequestHeader) ConnectionUpgrade() bool {
	h.parseRawHeaders()
	return hasHeaderValue(h.Peek("Connection"), strUpgrade)
}
func (h *RequestHeader) ConnectionUpgrade() bool {
	h.parseRawHeaders()
	return hasHeaderValue(h.Peek("Connection"), strUpgrade)
}
// ConnectionUpgrade returns true if 'Connection: Upgrade' header is set.