Merge "aconfig: make proto fields optional" am: a3b0027f am: 0201a71f am:...

Merge "aconfig: make proto fields optional" am: a3b0027f am: 0201a71f am: a3419690 am: 2302e3c4

Original change: https://android-review.googlesource.com/c/platform/build/+/2627237



Change-Id: I1f9325e9fd62d114ae3e7b3bae3b566f3a6c5e52
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>