title: Can we apply @FunctionalInterface annotation to abstract classes in Java?
body: <p>I know it can be applied on <strong>interface</strong> but as Interfaces with default methods ( Java 8+ Interfaces ) are very close now to abstract classes, Just wondering now can we use <strong>@FunctionalInterface with Abstract classes</strong>? </p>
  
  <p>If not why we can't?</p>