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

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

Change-Id: I2b4e019c71b3e28409ef6992eec0fcc93b33a38d
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>