code: private void findChildBeans(Object obj, MetaProperty<?> mp, Class<?> beanClass, Deque<Bean> temp) {
          if (obj != null) {
              if (obj instanceof Bean) {
                  temp.addFirst((Bean) obj);
              } else {
                  SerIterator it = SerIteratorFactory.INSTANCE.create(obj, mp, beanClass);
                  if (it != null) {
                      while (it.hasNext()) {
                          it.next();
                          findChildBeans(it.key(), mp, Object.class, temp);
                          findChildBeans(it.value(), mp, Object.class, temp);
                          findChildBeans(it.column(), mp, Object.class, temp);
                      }
                  }
              }
          }
      }
docs: find child beans, including those in collections