code: @SuppressWarnings({ "rawtypes", "unchecked" })
      private static boolean isAnnotated(final Class clazz) {
          Plugin plugin = (Plugin) clazz.getAnnotation(Plugin.class);
          return plugin != null;
      }
docs: Returns <code>true</code> if the class contains plugin annotations.
  
  @param clazz
  The plugin class
  
  @return <code>true</code> if the class contains plugin