stash-pullrequest-builder-plugin defines 10 variables, such as `sourceCommitHash`. Those variables are not available in multi-configuration jobs apart from the top-level process.

Those variable can be made available to the jobs by listing them in hudson.model.ParametersAction.safeParameters on the java command line. That's a workaround for SECURITY-170 that is no longer needed for free-style jobs.

Even with that workaround, Jenkins spams logs with messages like this:

WARNING: Skipped parameter `sourceCommitHash` as it is undefined on `TestRepository_pull_request_builder`. Set `-Dhudson.model.ParametersAction.keepUndefinedParameters=true` to allow undefined parameters to be injected as environment variables or `-Dhudson.model.ParametersAction.safeParameters=[comma-separated list]` to whitelist specific parameter names, even though it represents a security breach or `-Dhudson.model.ParametersAction.keepUndefinedParameters=false` to no longer show this message.

Only multi-configuration jobs appear in those messages. The way to suppress them is to also add -Dhudson.model.ParametersAction.keepUndefinedParameters=false to the java command line.

My expectations are:

• The variables defined by stash-pullrequest-builder-plugin should be available to multi-configuration jobs
• No warnings should be logged about those variables
• No java command line parameters should be needed to achieve it