Symfony version(s) affected: 3.4.12

Description
If i call $session->get('foo/bar/name') on a clean session I will end up with data in the session.
In my opinion a "get" should not create any entries.

How to reproduce

$session->get('foo/bar/name');
dump($session->get('foo'));

I would expect to see 'null' but i get an array containing "bar => null"