[mainline] Expose getTetherApnRequired API as system API

1. getTetherApnRequired API rename to isTetherApnRequired.
2. Expose isTetherApnRequired API as system API.

Bug: 142365448
Test: Build pass.
      atest TetheringConfigurationTest (PASS)

Change-Id: Iafb2e4fbddb0251e23673742d990ad098a8ae375

Tethering/src/com/android/server/connectivity/tethering/TetheringConfiguration.java

@@ -251,7 +251,7 @@ public class TetheringConfiguration {
     /** Check whether dun is required. */
     public static boolean checkDunRequired(Context ctx, int id) {
         final TelephonyManager tm = (TelephonyManager) ctx.getSystemService(TELEPHONY_SERVICE);
-        return (tm != null) ? tm.getTetherApnRequired(id) : false;
+        return (tm != null) ? tm.isTetherApnRequired(id) : false;
     }
 
     private static Collection<Integer> getUpstreamIfaceTypes(Resources res, boolean dunRequired) {

Tethering/tests/unit/src/com/android/server/connectivity/tethering/TetheringConfigurationTest.java

@@ -145,7 +145,7 @@ public class TetheringConfigurationTest {
 
     @Test
     public void testDunFromTelephonyManagerMeansDun() {
-        when(mTelephonyManager.getTetherApnRequired(anyInt())).thenReturn(true);
+        when(mTelephonyManager.isTetherApnRequired(anyInt())).thenReturn(true);
 
         final TetheringConfiguration cfgWifi = getTetheringConfiguration(TYPE_WIFI);
         final TetheringConfiguration cfgMobileWifiHipri = getTetheringConfiguration(
@@ -169,7 +169,7 @@ public class TetheringConfigurationTest {
 
     @Test
     public void testDunNotRequiredFromTelephonyManagerMeansNoDun() {
-        when(mTelephonyManager.getTetherApnRequired(anyInt())).thenReturn(false);
+        when(mTelephonyManager.isTetherApnRequired(anyInt())).thenReturn(false);
 
         final TetheringConfiguration cfgWifi = getTetheringConfiguration(TYPE_WIFI);
         final TetheringConfiguration cfgMobileWifiHipri = getTetheringConfiguration(
@@ -212,7 +212,7 @@ public class TetheringConfigurationTest {
     @Test
     public void testNoDefinedUpstreamTypesAddsEthernet() {
         when(mResources.getIntArray(config_tether_upstream_types)).thenReturn(new int[]{});
-        when(mTelephonyManager.getTetherApnRequired(anyInt())).thenReturn(false);
+        when(mTelephonyManager.isTetherApnRequired(anyInt())).thenReturn(false);
 
         final TetheringConfiguration cfg = new TetheringConfiguration(
                 mMockContext, mLog, INVALID_SUBSCRIPTION_ID);
@@ -235,7 +235,7 @@ public class TetheringConfigurationTest {
     public void testDefinedUpstreamTypesSansEthernetAddsEthernet() {
         when(mResources.getIntArray(config_tether_upstream_types)).thenReturn(
                 new int[]{TYPE_WIFI, TYPE_MOBILE_HIPRI});
-        when(mTelephonyManager.getTetherApnRequired(anyInt())).thenReturn(false);
+        when(mTelephonyManager.isTetherApnRequired(anyInt())).thenReturn(false);
 
         final TetheringConfiguration cfg = new TetheringConfiguration(
                 mMockContext, mLog, INVALID_SUBSCRIPTION_ID);
@@ -253,7 +253,7 @@ public class TetheringConfigurationTest {
     public void testDefinedUpstreamTypesWithEthernetDoesNotAddEthernet() {
         when(mResources.getIntArray(config_tether_upstream_types))
                 .thenReturn(new int[]{TYPE_WIFI, TYPE_ETHERNET, TYPE_MOBILE_HIPRI});
-        when(mTelephonyManager.getTetherApnRequired(anyInt())).thenReturn(false);
+        when(mTelephonyManager.isTetherApnRequired(anyInt())).thenReturn(false);
 
         final TetheringConfiguration cfg = new TetheringConfiguration(
                 mMockContext, mLog, INVALID_SUBSCRIPTION_ID);