Return empty file list when out is an empty string. am: 0482d26ce8 am: 719e9a5c20 am: ae65a3e744 am: b624d62700 am: 89f7dc21eb

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

Change-Id: Ie665e3729678cedb2ce596120827901fbc84ff44