Downgrade list of subIds in NetworkCapabilities to @SystemApi

This change downgrades API visibility for the list-of-subIds in the
NetworkCapabilities to SystemApi

Bug: 175662146
Test: atest NetworkCapabilitiesTest#testSubIds
Test: atest FrameworksNetTests
Change-Id: I372fa9eaa7585aefd1710948ca007456feedd578
diff --git a/framework/api/current.txt b/framework/api/current.txt
index 0a9560a..ab290f9 100644
--- a/framework/api/current.txt
+++ b/framework/api/current.txt
@@ -298,7 +298,6 @@
     method @Nullable public android.net.NetworkSpecifier getNetworkSpecifier();
     method public int getOwnerUid();
     method public int getSignalStrength();
-    method @NonNull public java.util.Set<java.lang.Integer> getSubIds();
     method @Nullable public android.net.TransportInfo getTransportInfo();
     method public boolean hasCapability(int);
     method public boolean hasTransport(int);
@@ -408,7 +407,6 @@
     method public android.net.NetworkRequest.Builder removeTransportType(int);
     method @Deprecated public android.net.NetworkRequest.Builder setNetworkSpecifier(String);
     method public android.net.NetworkRequest.Builder setNetworkSpecifier(android.net.NetworkSpecifier);
-    method @NonNull public android.net.NetworkRequest.Builder setSubIds(@NonNull java.util.Set<java.lang.Integer>);
   }
 
   public class ParseException extends java.lang.RuntimeException {
diff --git a/framework/api/system-current.txt b/framework/api/system-current.txt
index afd4fa0..251e5e8 100644
--- a/framework/api/system-current.txt
+++ b/framework/api/system-current.txt
@@ -274,6 +274,7 @@
   public final class NetworkCapabilities implements android.os.Parcelable {
     method @NonNull public int[] getAdministratorUids();
     method @Nullable public String getSsid();
+    method @NonNull public java.util.Set<java.lang.Integer> getSubIds();
     method @NonNull public int[] getTransportTypes();
     method public boolean isPrivateDnsBroken();
     method public boolean satisfiedByNetworkCapabilities(@Nullable android.net.NetworkCapabilities);
@@ -327,6 +328,7 @@
 
   public static class NetworkRequest.Builder {
     method @NonNull @RequiresPermission(android.Manifest.permission.NETWORK_SIGNAL_STRENGTH_WAKEUP) public android.net.NetworkRequest.Builder setSignalStrength(int);
+    method @NonNull public android.net.NetworkRequest.Builder setSubIds(@NonNull java.util.Set<java.lang.Integer>);
   }
 
   public final class NetworkScore implements android.os.Parcelable {