Is it even possible? HTTPS is used to avoid any possibility of man in the middle attack. How can nokia's proxy servers be able to decrypt that encrypted information unless they themselves have the private key?
It's a simple MITM attack, where the endpoint (your browser) has a whitelisted certificate for the proxy, so the browser is happy that it's talking to a correctly signed certificate that it trusts, and the proxy uses the the certificate for the other end of the connection.
http://www.paloaltonetworks.com/products/features/decryption...
It works for SSH too, if you are not careful about host keys and fingerprints.
I don't think that's what is happening, we need further explanation. Although if that is what is happening it;s really bad as they would effectively be impersonating the sites.