The Goal is to upgrade the CA API Gateway 9.2 CR 07 to 9.2 CR09 following the below documented process:
https://docops.ca.com/ca-api-gateway/9-2/en/install-configure-upgrade/upgrade-the-gateway/upgrade-an-appliance-gateway

When one go over the below link:
https://docops.ca.com/ca-api-gateway/9-2/en/install-configure-upgrade/upgrade-the-gateway/upgrade-an-appliance-gateway

It was recommended to verify that this upgrade won't break any of our custom assertions.

What one would need to do in such a case?

The environment is CA API Gateway 9.2 CR07 with custom assertions.

When upgrading between CR's - custom assertions normally do not need any change.

With regards to the specific CA API Gateway CR09:
https://docops.ca.com/ca-api-gateway/9-2/en/release-notes-9-2/resolved-issues#ResolvedIssues-IssuesResolvedinVersion9.2CR9

One would need to re-test (re-compile) against the JDK 1.8.0_172 version as the Java version has changed and also some Java Security options related to this specific Java version.