title: What is mean by Collection<? extends EmpApp>?
body: <p>In my code i am using two different class objects <strong>empobj</strong> &amp; <strong>employee</strong>.
  Eclipse asks to change the code</p>
  
  <pre><code>empobj.addAll(employee);
  </code></pre>
  
  <p>to</p>
  
  <pre><code>empobj.addAll((Collection&lt;? extends EmpApp&gt;) employee);
  </code></pre>
  
  <p>What does it mean? 
  I cannot understand the concept here.
  Can I get any clarifications about this?</p>