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interface UnmodifiableInterface {
  SensitiveMutable unmodifiableView(SensitiveMutable sm);
}

class UnmodifiableSensitiveMutable extends SensitiveMutable  {
  int[] array = new int[10];

  public void setArray(int[] i) {
    throw new UnsupportedOperationException();
  }
}

class UnmodifiableWrapper extends UnmodifiableSensitiveMutable implements UnmodifiableInterface {
  public SensitiveMutable unmodifiableView(SensitiveMutable sm) { 
    return new UnmodifiableWrapper(); // subtype of SensitiveMutable
  }
}

class Invoker {
  public static void main(String[] args) {
    UnmodifiableWrapper uw = new UnmodifiableWrapper();
    SensitiveMutable s = uw.unmodifiableView(sm);
    s.setArray(new int[10]); // throws UnsupportedOperationException unlike s.getArray()    
  }
}