<p>Protected methods that are never used by any classes in the same
  project are strongly suspected to be dead code. Dead code means
  unnecessary, inoperative code that should be removed. This helps in
  maintenance by decreasing the maintained code size, making it easier to
  understand the program and preventing bugs from being introduced.</p>
<p>In the following case, unused protected methods are not
  considered as dead code by SonarQube :</p>
<ul>
  <li>Protected methods which override a method from a parent class.</li>
  <li>Protected methods of an abstract class.</li>
</ul>