Sets a callback that will decide whether to accept a secure connection with a server certificate that cannot be authenticated by any of our trusted root certificates.
When an secure HTTP request if made, using this HttpClient, and the
server returns a server certificate that cannot be authenticated, the
callback is called asynchronously with the X509Certificate object and
the server's hostname and port. If the value of badCertificateCallback
is null, the bad certificate is rejected, as if the callback
returned false
If the callback returns true, the secure connection is accepted and the
Future<HttpClientRequest> that was returned from the call making the
request completes with a valid HttpRequest object. If the callback returns
false, the Future<HttpClientRequest> completes with an exception.
If a bad certificate is received on a connection attempt, the library calls the function that was the value of badCertificateCallback at the time the request is made, even if the value of badCertificateCallback has changed since then.