How do you add an absolute path to application start scripts?

Hi I have a runtime dependency on an absolute directory outside of my application.
I’ve added it as

runtime files('/foo/bar/prod/conf')

And in my createScript I have:
classpath = jar.outputs.files + project.configurations.runtime

But the generated runScript keeps stripping out my path and replacing it with:

How do I get it to keep the absolute path?