OidcSessionRegistry nullability issues

Describe the bug
When upgrading to spring-security 7.1.0 a custom OidcSessionRegistry can no longer be built in Kotlin.
The documentation for org.springframework.security.oauth2.client.oidc.session.OidcSessionRegistry#removeSessionInformation(java.lang.String) mentions that the result could be null:

Returns: any found OidcSessionInformation, could be null

However, due to the presence of jspecify annotations in the package, the return type must never be null.

To Reproduce
Create a custom implementation of OidcSessionRegistry in kotlin, and observe that the below signature no longer compiles:

override fun removeSessionInformation(clientSessionId: String): OidcSessionInformation?

Expected behavior
org.springframework.security.oauth2.client.oidc.session.OidcSessionRegistry#removeSessionInformation(java.lang.String should declare a nullable return value, as the documentation otherwise specifies

Sample

N/A

Start with the removeSessionInformation method in oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/oidc/session/OidcSessionRegistry.java, using the linked source location. Check the package nullability annotations against the documented nullable result, then verify that a Kotlin implementation with a nullable return type compiles and that the API documentation remains consistent.