var golang.org/x/net/http2.errExtendedConnectNotSupported

2 uses

	golang.org/x/net/http2 (current package)
		transport.go#L1435: var errExtendedConnectNotSupported = errors.New("net/http: extended connect not supported by peer")
		transport.go#L1469: 				return errExtendedConnectNotSupported