Hibernate configuration file error prompt, the content of element type "list" must match "(Meta*,subselect?,cache?,synchroniz

I found this problem when I was writing a model class mapping file.

When mapping a list collection, you need to have the elements

Key, (Index | list-index), (element
| One-to-many | Many-to-many | composite-element | Many-to-any)

Indispensable, of course, more can not ...

For example, if you have element elements, you cannot add a pair or more to a relationship.

With a one-to-many relationship, you cannot add element elements.

When this error is reported, it is better than the formula above to see which one is missing and which is more.

Attached to an example I wrote myself

<list name= "Replys" table= "Replys" >
			<key column= "artical_id" not-null= "true"/>
			<list-index column= "Order"/>
			<one-to-many class= "model. Reply "/>
		</list>