Fix type issues after shading jetty in test server

[bric3]

What Does This Do

After #10218, some code needed to be updated. This was not caught by the IDE due to dynamic nature of Groovy.

Motivation

Additional Notes

Contributor Checklist

• Format the title according the contribution guidelines
• Assign the type: and (comp: or inst:) labels in addition to any useful labels
• Don't use close, fix or any linking keywords when referencing an issue.
  Use solves instead, and assign the PR milestone to the issue
• Update the CODEOWNERS file on source file addition, move, or deletion
• Update the public documentation in case of new configuration flag or behavior

Jira ticket: [PROJ-IDENT]

[PerfectSlayer]

Thanks for the fix!