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

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



Change-Id: Ib293c14f746b29c208601caa1783a8292494cb7a
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>