New method that supports CTS test case to check the file contents remains unaltered. am: 567f2b4378 am: ae1a2d3558 am: 9d67cd3da9 am: 577604ee25

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/services/Telephony/+/22838863

Change-Id: I8d6609f78f1f40d385dc22d35341f669d4903c8d
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>