Meta annotation for relational annotations, to be used on an annotation.
 
 The following example shows how a relational annotation can be created and
 used. The Orderid annotation indicates there is a relation between
 OrderEvent and OrderLineEvent. if they have the same ID,
 the order line belongs to the order.
 
@MetadataDefinition
@Relational
@Name("com.example.OrderId")
@Label("Order ID")
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
public @interface OrderId {
}
@Name("com.example.Order")
@Label("Order")
@Category("Orders")
class OrderEvent extends Event {
    @Label("Order ID")
    @OrderId
    long orderId;
    @Label("Order Date")
    @Timestamp
    long orderDate;
}
@Name("com.example.OrderLine")
@Label("Order Line")
@Category("Orders")
class OrderLineEvent extends Event {
    @Label("Order ID")
    @OrderId
    long orderId;
    @Label("Quantity")
    long quantity;
    @Label("Product")
    String product;
}
- Since:
- 9