Don't worry about this as it is mentioned on the Xenforo Official site:
Note: If you decide to patch the files instead of doing full upgrades, your "File health check" will report these files as having "Unexpected contents". Because these files no longer contain the same contents your version of XF was shipped with, this is expected and can be safely ignored.
BTW, If you want to remove it you can get the hash using this command
Code:
sha256sum src/XF/Api/App.php
get those hashes and update them on -
src > addons > XF > hashes.json
Another way is delete those lines from
hashes.json
file