原因是最终运行的DefaultSaveOrUpdateEventListener. performUpdate（

persistenceContext.addEntity(
        entity,
        ( persister.isMutable() ? Status.MANAGED : Status.READ_ONLY ),
        null, // <-- this is the 'loadedState'
        key,
        persister.getVersion( entity ),
        LockMode.NONE,
        true,
        persister,
        false
);

因此将创建一个loadedState为null的EntityEntry。稍后，当LazyAttributeLoadingInterceptor加载该集合并尝试替换该属性的已加载状态时，

assert loadedState != null;

火灾。
我不确定这是否是Hibernate的bug，或者我们的代码只是以Hibernate不支持的方式加载/管理实体。

public class LazyAttributeSaveOrUpdateEventListener implements SaveOrUpdateEventListener {

    public static final LazyAttributeSaveOrUpdateEventListener INSTANCE = new LazyAttributeSaveOrUpdateEventListener();
    private static final long serialVersionUID = 1L;
    private static final Log LOGGER = LogFactory.getLog(LazyAttributeSaveOrUpdateEventListener.class);

    private final transient Field loadedStateField;

    LazyAttributeSaveOrUpdateEventListener() {
        loadedStateField = ReflectionUtils.findField(AbstractEntityEntry.class, "loadedState");
    }

    @Override
    public void onSaveOrUpdate(SaveOrUpdateEvent event) throws HibernateException {
        if (event.getEntity() instanceof PersistentAttributeInterceptable) {
            initializeLoadedState(event);
        }
    }

    private void initializeLoadedState(SaveOrUpdateEvent event) {
        final EntityEntry entry = getEntityEntry(event);
        final Object[] loadedState = entry.getLoadedState();
        if (loadedState == null && entry.getStatus() != Status.READ_ONLY) {
            // if accessing a lazy-loaded collection on this entity, org.hibernate.persister.entity.AbstractEntityPersister.initializeLazyProperty()
            // will try to re-set the loaded state, resulting in an AssertionError if loadedState is null
            LOGGER.debug("Got empty loaded state for " + event.getEntity());
            EntityPersister persister = entry.getPersister();
            Object[] stubLoadedValue = ArrayHelper.filledArray(
                null,
                Object.class,
                persister.getPropertyTypes().length);
            ReflectionUtils.makeAccessible(loadedStateField);
            ReflectionUtils.setField(loadedStateField, entry, stubLoadedValue);
        }
    }

    private EntityEntry getEntityEntry(SaveOrUpdateEvent event) {
        return Optional.ofNullable(event.getEntry())
            .orElseGet(() -> {
                final PersistenceContext persistenceContext = event.getSession().getPersistenceContextInternal();
                return persistenceContext.getEntry(event.getEntity());
            });
    }

}

并将其注册为

eventListenerRegistry.appendListeners(EventType.SAVE_UPDATE, LazyAttributeSaveOrUpdateEventListener.INSTANCE);

我曾担心创建一个空初始化的加载状态会带来负面影响，但到目前为止一切似乎都正常。