Description of problem:

After upgrading to Satellite 6.16, we are no longer able to access Content -> Subscriptions.

The following error message is displayed:
~~~
Katello::Resources::Candlepin::Pool: 500 Internal Server Error {"displayMessage":"Runtime Error Cannot invoke \"java.lang.Boolean.booleanValue()\" because \"this.managed\" is null at org.candlepin.model.Pool.isManaged:1,333","requestUuid":"7b291bd1-ca79-4c0c-b0e9-fe0c5c0cd710"} (GET /candlepin/pools/8a21e79a74ba33870174e8f629220435)
~~~

The page shows:
~~~
There are no Subscriptions to display
Add subscriptions using the Add Subscriptions button.
~~~

How reproducible:

Is this issue a regression from an earlier version:

Please refer to CANDLEPIN Jira issue already resolved : https://issues.redhat.com/browse/CANDLEPIN-940

Business Impact / Additional info:

QE Tracker for https://issues.redhat.com/browse/SAT-29355