Replace Preconditions.checkNotNull with Objects.requireNonNull

IpSec service is going to be moved into Connectivity module. Replace
Preconditions.checkNotNull with Objects.requireNonNull to remove
hidden API usages.

Bug: 204153604
Test: FrameworksNetTests
Change-Id: Iff7f76844d4126b0e17b62b4ce821449b5b6ce44
2 files changed
tree: f573f2445850f1ca5dc23cae4f43c58d4aa2c204
  1. framework/
  2. framework-t/
  3. service-t/
  4. services/
  5. tests/