code: private static void filterClasses(final Collection<Class<?>> classes) {
          final Iterator<Class<?>> iterator = classes.iterator();
          while (iterator.hasNext()) {
              final Class<?> clazz = iterator.next();
              if (clazz.isAnnotation() || !Reflections.isConcrete(clazz)) {
                  iterator.remove();
              }
          }
      }
docs: Filters no-bean classes with the specified classes.
  <p>
  A valid bean is <b>NOT</b>:
  <ul>
  <li>an annotation</li>
  <li>interface</li>
  <li>abstract</li>
  </ul>
  
  @param classes the specified classes to filter