Unhide IpPrefix(InetAddress, int)

Unhide IpPrefix constructor to allow its usage with the new
VpnService.Builder#excludeRoute(IpPrefix) method.

Bug: 186082280
Test: atest IpPrefixTest
Change-Id: Ie5b62b2b206def1be53a41219681b4a8bc06c1d2

framework/api/current.txt

@@ -206,6 +206,7 @@ package android.net {
   }
 
   public final class IpPrefix implements android.os.Parcelable {
+    ctor public IpPrefix(@NonNull java.net.InetAddress, @IntRange(from=0, to=128) int);
     method public boolean contains(@NonNull java.net.InetAddress);
     method public int describeContents();
     method @NonNull public java.net.InetAddress getAddress();

framework/api/system-current.txt

@@ -131,7 +131,6 @@ package android.net {
   }
 
   public final class IpPrefix implements android.os.Parcelable {
-    ctor public IpPrefix(@NonNull java.net.InetAddress, @IntRange(from=0, to=128) int);
     ctor public IpPrefix(@NonNull String);
   }
 

framework/src/android/net/IpPrefix.java

@@ -87,9 +87,7 @@ public final class IpPrefix implements Parcelable {
      *
      * @param address the IP address. Must be non-null.
      * @param prefixLength the prefix length. Must be >= 0 and <= (32 or 128) (IPv4 or IPv6).
-     * @hide
      */
-    @SystemApi
     public IpPrefix(@NonNull InetAddress address, @IntRange(from = 0, to = 128) int prefixLength) {
         // We don't reuse the (byte[], int) constructor because it calls clone() on the byte array,
         // which is unnecessary because getAddress() already returns a clone.

tests/common/java/android/net/IpPrefixTest.java

@@ -122,6 +122,9 @@ public class IpPrefixTest {
 
         p = new IpPrefix("[2001:db8::123]/64");
         assertEquals("2001:db8::/64", p.toString());
+
+        p = new IpPrefix(InetAddresses.parseNumericAddress("::128"), 64);
+        assertEquals("::/64", p.toString());
     }
 
     @Test