Return empty file list when out is an empty string. am: 0482d26ce8 am: 719e9a5c20 am: c45a020209

Original change: https://googleplex-android-review.googlesource.com/c/platform/test/vts-testcase/vndk/+/12280289

Change-Id: I0806c2f8fc7a6dee5f55e47404e1686f9e9b9d0b