code: public static void validateSslCertificate() {
          final NetworkHttpClient client = new NetworkHttpClient();
          final Request request = new Request(HttpMethod.GET, "https://api.twilio.com:8443");
  
          try {
              final Response response = client.makeRequest(request);
  
              if (!TwilioRestClient.SUCCESS.apply(response.getStatusCode())) {
                  throw new CertificateValidationException(
                      "Unexpected response from certificate endpoint", request, response
                  );
              }
          } catch (final ApiException e) {
              throw new CertificateValidationException("Could not get response from certificate endpoint", request);
          }
      }
docs: Validate that we can connect to the new SSL certificate posted on api.twilio.com.
  
  @throws com.twilio.exception.CertificateValidationException if the connection fails