Tidy up libcore.timezone APIs

Tidy up the libcore.timezone APIs to make them as close as possible to
android.timezone. In future, these classes should be repackages to be
the actual android.timezone classes, so the APIs need to be in sync.

Bug: 148086409
Test: treehugger
Change-Id: Ic312dd70094134229b276549f055e8341af54122
diff --git a/tests/CarDeveloperOptions/src/com/android/car/developeroptions/datetime/timezone/model/FilteredCountryTimeZones.java b/tests/CarDeveloperOptions/src/com/android/car/developeroptions/datetime/timezone/model/FilteredCountryTimeZones.java
index b8a56c6..48f7ab3 100644
--- a/tests/CarDeveloperOptions/src/com/android/car/developeroptions/datetime/timezone/model/FilteredCountryTimeZones.java
+++ b/tests/CarDeveloperOptions/src/com/android/car/developeroptions/datetime/timezone/model/FilteredCountryTimeZones.java
@@ -48,9 +48,10 @@
         mCountryTimeZones = countryTimeZones;
         List<String> timeZoneIds = countryTimeZones.getTimeZoneMappings().stream()
                 .filter(timeZoneMapping ->
-                        timeZoneMapping.showInPicker && (timeZoneMapping.notUsedAfter == null
-                                || timeZoneMapping.notUsedAfter >= MIN_USE_DATE_OF_TIMEZONE))
-                .map(timeZoneMapping -> timeZoneMapping.timeZoneId)
+                        timeZoneMapping.isShownInPicker()
+                                && (timeZoneMapping.getNotUsedAfter() == null
+                                || timeZoneMapping.getNotUsedAfter() >= MIN_USE_DATE_OF_TIMEZONE))
+                .map(timeZoneMapping -> timeZoneMapping.getTimeZoneId())
                 .collect(Collectors.toList());
         mTimeZoneIds = Collections.unmodifiableList(timeZoneIds);
     }