Upgrading SDK from 15 to 21, how to figure out where things are at

Questions
1

We are finally getting around to upgrading okta SDK from 15 to latest 21.

Now things are missing or moved.
One example is this
com.okta.sdk.resource.api.CustomizationApi;

Looks like it was in version 17 but gone in 18.

What is the best way to know where things are now. Google only helps you if you know what to search for.
Thanks

2

Getting frustrated or not understanding the changes.

Old way we used AuthorizationServerPolicyRule and that seems to still exist.
But to create an Authorization Server Policy I need new? AuthorizationServerPolicyRuleRequest.

Trying to mock listAuthorizationServerPolicyRules which is the old way??

Why the change?