diff --git a/core/java/android/net/UnderlyingNetworkInfo.java b/core/java/android/net/UnderlyingNetworkInfo.java
index 8fb4832..7bf9231 100644
--- a/core/java/android/net/UnderlyingNetworkInfo.java
+++ b/core/java/android/net/UnderlyingNetworkInfo.java
@@ -16,11 +16,15 @@
 
 package android.net;
 
+import static android.annotation.SystemApi.Client.MODULE_LIBRARIES;
+
 import android.annotation.NonNull;
+import android.annotation.SystemApi;
 import android.os.Parcel;
 import android.os.Parcelable;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 import java.util.Objects;
 
@@ -30,6 +34,7 @@
  *
  * @hide
  */
+@SystemApi(client = MODULE_LIBRARIES)
 public final class UnderlyingNetworkInfo implements Parcelable {
     /** The owner of this network. */
     public final int ownerUid;
@@ -46,7 +51,7 @@
         Objects.requireNonNull(underlyingIfaces);
         this.ownerUid = ownerUid;
         this.iface = iface;
-        this.underlyingIfaces = underlyingIfaces;
+        this.underlyingIfaces = Collections.unmodifiableList(new ArrayList<>(underlyingIfaces));
     }
 
     private UnderlyingNetworkInfo(@NonNull Parcel in) {