Merge "Throw IllegalStateException when inserting an existing item" into main am: e7d67662a9

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/3254276

Change-Id: Id2a9b26993197ae487d476df47d071a7d4665a09
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>