Treat hidden API exemptions as whitelist.

Update docs accordingly.

Test: m
Bug: 64382372
Change-Id: Ief8daf3badeb046b0461a3ebcd289e242d559070
diff --git a/core/java/android/os/ZygoteProcess.java b/core/java/android/os/ZygoteProcess.java
index b9dd376..d1d5d8e 100644
--- a/core/java/android/os/ZygoteProcess.java
+++ b/core/java/android/os/ZygoteProcess.java
@@ -467,7 +467,8 @@
      * <p>The list of exemptions will take affect for all new processes forked from the zygote after
      * this call.
      *
-     * @param exemptions List of hidden API exemption prefixes.
+     * @param exemptions List of hidden API exemption prefixes. Any matching members are treated as
+     *        whitelisted/public APIs (i.e. allowed, no logging of usage).
      */
     public void setApiBlacklistExemptions(List<String> exemptions) {
         synchronized (mLock) {