New method that supports CTS test case to check the file contents remains unaltered. am: 567f2b4378 am: d4a09f8b36 am: 7e899a2939 am: f85208d045

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

Change-Id: I89ad5b25793413dda6597502c0b5ab0de4888e5a
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>