JENKINS-67173 proposes the removal of support of agent-to-controller FilePath access.

https://github.com/jenkinsci/hpe-application-automation-tools-plugin/blob/1f23f14a5507c237b499782989c372038bcab673/src/main/java/com/microfocus/application/automation/tools/octane/tests/junit/JUnitExtension.java#L183 implements that by having a Callable sent from controller to agent, and accessing a FilePath on the controller.