Fix -Wnullable-to-nonnull-conversion errors am: 4730f0d7 am: 2e514606 am:...

Fix -Wnullable-to-nonnull-conversion errors am: 4730f0d7 am: 2e514606 am: 61fb9c2b am: 9ae362b5 am: 6c2b551d am: 9d744816

Original change: https://android-review.googlesource.com/c/platform/packages/modules/DnsResolver/+/2582958



Change-Id: I274afc968a0d5a1b52d874d90a124b1c091349f0
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>