Return empty file list when out is an empty string. am: 0482d26ce8 am: 719e9a5c20 am: ae65a3e744 am: 176aef2b4f am: 0e9623bd29

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

Change-Id: I9fc553103eb5cc6d7e25f1e016bc66260ba849e7