api-review: add @Nullable and @Nonull for return value of Passpoint APIs

Bug: 126702500
Test: ./frameworks/base/wifi/tests/runtests.sh
Change-Id: Iec5985d7fdaaa6fa953230444a9aa490dfd73b7b
Signed-off-by: Ecco Park <eccopark@google.com>
2 files changed