code: private static EquivalentAddressGroup flattenEquivalentAddressGroup(
        List<EquivalentAddressGroup> groupList, Attributes attrs) {
      List<SocketAddress> addrs = new ArrayList<>();
      for (EquivalentAddressGroup group : groupList) {
        addrs.addAll(group.getAddresses());
      }
      return new EquivalentAddressGroup(addrs, attrs);
    }
docs: Flattens list of EquivalentAddressGroup objects into one EquivalentAddressGroup object.