[CM] Fix NPE due to unvalidated callback value

Fix flaky test resulting from the above fix.

Bug: 132950880
Test: atest ConnectivityServiceTest
Change-Id: I1ddf3bb016239bf88cdd8843a71dcb5e582e83ac
1 file changed
tree: f2663c308ee8dc8135dc9145fe49c2bb14ca0d03
  1. core/
  2. services/
  3. tests/