title: return type required for overridden method
body: <p>I have the following Class</p>
  
  <pre><code>class Stack {
      Node top = null;
      ...
      public Node pop(){ 
          return this.top;
      }
  }
  
  class MinStack extends Stack {
      ...
      public Node pop() {
          super.pop();
      }
  }
  </code></pre>
  
  <p>Compiler says that <code>pop()</code> in <code>MinStack</code> needs return type of <code>Node</code>. Isn't that implemented by <code>super.pop()</code>?</p>