public static Class<?> getUserClass(Class<?> clazz) {
        // Forked from https://github.com/spring-projects/spring-framework/blob/1565f4b83e7c48eeec9dc74f7eb042dce4dbb49a/spring-core/src/main/java/org/springframework/util/ClassUtils.java#L896-L904
        if (clazz.getName().contains(CGLIB_CLASS_SEPARATOR)) {
            final Class<?> superclass = clazz.getSuperclass();
            if (superclass != null && superclass != Object.class) {
                return superclass;
            }
        }
        return clazz;
    }
Returns the user-defined class for the given class: usually simply the given class,
but the original class in case of a CGLIB-generated subclass.
core/src/main/java/com/linecorp/armeria/internal/server/annotation/ClassUtil.java