dialing      map[string]*http2dialCall     // currently in-flight dials
	keys         map[*http2ClientConn][]string
	addConnCalls map[string]*http2addConnCall // in-flight addConnIfNeeded calls
}

func (p *http2clientConnPool) GetClientConn(req *Request, addr string) (*http2ClientConn, error) {
	return p.getClientConn(req, addr, http2dialOnMiss)
}

const (
	http2dialOnMiss   = true