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

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

Change-Id: I6bf0c5f2b01b79d375e305142720845810db6359