Empty filesystem contains a "work" dir (that shouldn't be there)

Hi,
first of all, thanks for this library. I'm trying to use it, but the following code (in Kotlin)...

`val fs = Jimfs.newFileSystem(Configuration.unix())`
`val rootDir = fs.getPath("/")`
`Files.newDirectoryStream(rootDir).forEach { println(it) }`

...prints...

`/work`

Am I doing something wrong? As far as I can understand, that dir shouldn't be there.

Thanks again for your work!