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

Fix -Wnullable-to-nonnull-conversion errors am: 47936dd7 am: f3aefe4f am: 4cd11bc4 am: d00eca81 am: 2fc54372 am: 2acc76a9

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



Change-Id: Ic59235462df74193c2e5e8210119f51a9259e0b7
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>