Added annotations to the API

Added @NonNull and @Nullable to APIs.

Test: Build
Bug: 126702898

Merged-In: I697298837858829bb0851aba389159701fa0fc5e
Change-Id: I697298837858829bb0851aba389159701fa0fc5e
(cherry picked from commit 1eb3f0cdaed5a7156e9dcb11223f7f4ac82f1360)
2 files changed