My progress...
The root CA needed by IGN certificate is "Certigna", which is not present in Java JRE cacerts.
I've included the root CA certificate of Certigna in Java cacerts.
If I run RouteConverter for macOS, it don't works again...
BUT, if in run Linux version of RC under macOS (with java -jar RouteConverterLinux.jar), it works !
So, I supposed is it because the cacerts used by RouteConverterMacOpenSource.app is in app, not in /Library/... and yes, it is.
I imported the Certigna root CA certificate in the cacerts file included in the app, and...
... it works now !
So the conclusion : it is necessary and sufficient to import the Certigna root CA certificate in the trust store of the Java JRE.
For the macOS version, the trust store is included in app, so, I can do it only "manually", but I'm sure you can do it definitively for me ... !
Best regards
The root CA needed by IGN certificate is "Certigna", which is not present in Java JRE cacerts.
I've included the root CA certificate of Certigna in Java cacerts.
If I run RouteConverter for macOS, it don't works again...
BUT, if in run Linux version of RC under macOS (with java -jar RouteConverterLinux.jar), it works !
So, I supposed is it because the cacerts used by RouteConverterMacOpenSource.app is in app, not in /Library/... and yes, it is.
I imported the Certigna root CA certificate in the cacerts file included in the app, and...
... it works now !
So the conclusion : it is necessary and sufficient to import the Certigna root CA certificate in the trust store of the Java JRE.
For the macOS version, the trust store is included in app, so, I can do it only "manually", but I'm sure you can do it definitively for me ... !
Best regards