[LIVY-1064] Initial changes to provide Scala 2.13 compatibility

[idzikovsky]

What changes were proposed in this pull request?

I've stared working on Spark 4 compatibility in my local fork. I don't think that all changes that I've made is applicable to be pushed to the upstream project, but this change I'm confident about.

In this fix I mainly updated usage of collections to be compatible with new redesigned Scala 2.13 collections (so as with older Scala 2.11/2.12 collections).

Also, I replaced invocation of ServletContext.initParameters() with ServletContext.setInitParameter(), because the old wrapper is not compatible with a new jakarta.servlet.ServletContext interface (Spark 4 migrated from javax to jakarta), while ServletContext.setInitParameter() is version-independent.

How was this patch tested?

I run unit tests and manually tested that I'm able to create a Session.

Was this patch authored or co-authored using generative AI tooling?

Generated-by: Claude Opus 4.8.

[gyogal]

Thank you for your contribution @idzikovsky ! Scala 2.13 compatibility is an important requirement for LIVY-1041 (Add support for Spark 4 via a new Maven profile). Since that JIRA is already assigned to @roczei whose work in progress can be tracked at roczei#3 , could you please create a subtask for your changes (Scala 2.13 support) under LIVY-1041 in the JIRA? That way we could use the new ticket to merge your PR before merging the rest of the code changes required for Spark 4 support (currently being worked on by @roczei).

[idzikovsky]

Thanks @gyogal for your feedback!

Here is the JIRA subtask:
https://issues.apache.org/jira/browse/LIVY-1064

Also, I've force-pushed the commit with the right commit message.

Anything else that needs to be done?

[gyogal]

The JIRA looks good, thank you for making the updates @idzikovsky!