Fix -Wnullable-to-nonnull-conversion errors am: 47936dd7 am: f3aefe4f am:...

Fix -Wnullable-to-nonnull-conversion errors am: 47936dd7 am: f3aefe4f am: 82e66960 am: 0cd6dbd9

Original change: https://android-review.googlesource.com/c/platform/packages/modules/DnsResolver/+/2526839



Change-Id: I84946490ceceb97a0ed2c5c486b867290dca928b
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>