Add null checker for ServiceDataMap am: ebb3339846

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/18383452

Change-Id: Iff1ea25562fbfdca189ab9acf3e632d71459e5c1
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>