The sessions have no time limit.
If you see that the client reopens a session, it must be because the previous one has been closed for some issue. Apart from a Server crash, such an issue would be related to the single client, not to the Java Adapter.
A too long stalled state may cause session termination and reopening.
A resume of the possible state transitions for web clients can be found in the documentation for onStatusChange.

So, you should first identify the cause of your disconnections, then see if you can prevent them.