apollo-common/src/main/java/com/ctrip/framework/apollo/common/utils/BeanUtils.java/BeanUtils/deepFindField
class BeanUtils:  private static Field deepFindField(Class<?> clazz, String key) {
    Field field = null;
    while (!clazz.getName().equals(Object.class.getName())) {
      try {
        field = clazz.getDeclaredField(key);
        if (field != null) {
          break;
        }
      } catch (Exception e) {
        clazz = clazz.getSuperclass();
      }
    }
    return field;
  }