Non expiring sessions expiring after 5 minutes

[nfawcett]

Describe the bug
Updating from spring-session 3.3.5 to 3.4.1 causes non expiring sessions to expire after 5 minutes of inactivity.

To Reproduce

• RedisIndexedSessionRepository configured with maxInactiveIntervalInSeconds = -1.
• Call rest controller to create new session.
• Inspect TTL on spring:session:sessions:{{sessionId}}. TTL counts down from 300.
• With 5 minutes of inactivity session will expire.

Expected behavior
From version 3.3.5 TTL of spring:session:sessions:{{sessionId}} remains -1.

The issue looks to be related to this commit, here.

Sample
https://github.com/nfawcett/spring-session-expiring-issue. Change versions to see difference in behaviour.

[nfawcett]

The same issue has been reported here #3362. Apologies for the tag @rwinch but could this be looked at?