title: How to return a list of extends wildcard?
body: <p>I have the following method</p>
  
  <pre><code>public List&lt;? extends FooInterface&lt;X,Y&gt;&gt; getList()
  </code></pre>
  
  <p>in a class that has as a member a list:</p>
  
  <pre><code>List&lt;FooImplementation&gt; foolist = new ArrayList&lt;&gt;();
  </code></pre>
  
  <p>and i'm trying to do something like:</p>
  
  <pre><code>public List&lt;? extends FooInterface&lt;X,Y&gt;&gt; getList(){
      return foolist;
  }
  </code></pre>
  
  <p>but it does not work.</p>
  
  <p>The error is : </p>
  
  <pre><code>Incompatible types. 
  Required List&lt;? extends FooInterface&lt;X,Y&gt;&gt; 
  Found List&lt;FooImplementation&gt;.
  </code></pre>
  
  <p>What is wrong with it? I also tried to copy the foolist into a list of extends wildcards but that proved to be a fool's errand.</p>