Treat hidden API exemptions as whitelist.

Update docs accordingly.

Test: m
Bug: 64382372
Merged-In: Iaf83b3fb29208e9182f2b36a2189a8e5aa8171d4
Change-Id: Iaf83b3fb29208e9182f2b36a2189a8e5aa8171d4
(cherry picked from commit 6615f1a549378172c43a67eaa2608ed9c65e7449)
1 file changed