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

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

Change-Id: Icfec0a2c1418a2d18a11f11da3562b8582108cef
Signed-off-by: Automerger Merge Worker <[email protected]>