--- old/src/java.base/share/classes/sun/nio/ch/MembershipKeyImpl.java	2020-01-06 11:04:32.000000000 +0000
+++ new/src/java.base/share/classes/sun/nio/ch/MembershipKeyImpl.java	2020-01-06 11:04:32.000000000 +0000
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 2020, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -63,6 +63,10 @@
         this.source = source;
     }
 
+    int interfaceIndex() {
+        return interf.getIndex();
+    }
+
     /**
      * MembershipKey will additional context for IPv4 membership
      */
@@ -103,7 +107,6 @@
      */
     static class Type6 extends MembershipKeyImpl {
         private final byte[] groupAddress;
-        private final int index;
         private final byte[] sourceAddress;
 
         Type6(MulticastChannel ch,
@@ -111,12 +114,10 @@
               NetworkInterface interf,
               InetAddress source,
               byte[] groupAddress,
-              int index,
               byte[] sourceAddress)
         {
             super(ch, group, interf, source);
             this.groupAddress = groupAddress;
-            this.index = index;
             this.sourceAddress = sourceAddress;
         }
 
@@ -124,10 +125,6 @@
             return groupAddress;
         }
 
-        int index() {
-            return index;
-        }
-
         byte[] source() {
             return sourceAddress;
         }