validateConnection method
Atomically validates that host:port presents a certificate matching
the configured pins. The platform composes fetchCertificate and
verify inside a single channel call, so the certificate never enters
the Dart isolate.
When timeoutMs is non-null and positive, the platform throws
FETCH_CERTIFICATE_TIMEOUT if the combined operation exceeds it.
When instanceId is null, the global default instance is used.
Implementation
Future<void> validateConnection(
String host, {
int port = 443,
int? timeoutMs,
String? instanceId,
}) {
throw UnimplementedError('validateConnection() has not been implemented.');
}