Add nullability annotations to java.security.MessageDigest.

Points of note:
 - It is theoretically possible to construct an instance where the
   algorithm is null, but it seems clear that doing this is not
   intended, so this change treats it as @NonNull everywhere. (Forcing
   users to null-check the return of getAlgorithm(), for example,
   would not be helpful.)
 - This class itself does not prevent digest() returning a null array,
   but the jvadoc implies that it won't, so again this change treats
   it as @NonNull.

Bug: 64930165
Test: make core-current-stubs-nullability-validation-check-nullability-warnings

0 files changed, 0 insertions, 0 deletions