New method that supports CTS test case to check the file contents remains unaltered. am: 567f2b4378 am: ae1a2d3558 am: ef978156ba am: d53f14ac2d

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

Change-Id: I51f2af4dae43ad10c7b85058f688f0a194293f7d
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>