Update Distributed-Event-Bus.md

docs/en/Distributed-Event-Bus.md

@@ -342,6 +342,8 @@ public class ProductSynchronizer : EntitySynchronizer<OrderProduct, Guid, Produc
 
 The main point of this class is it subscribes to the create, update and delete events of the source entity and updates the local entity in the database. It uses the [Object Mapper](Object-To-Object-Mapping.md) system to create or update the `OrderProduct` objects from `ProductEto` objects. So, you should also configure the object mapper to make it properly works. Otherwise, you should manually perform the object mapping by overriding the `MapToEntityAsync(TSourceEntityEto)` and `MapToEntityAsync(TSourceEntityEto,TEntity)` methods in your `ProductSynchronizer` class.
 
+If your entity has a composite primary key (see the [Entities document](Entities.md)), then you should inherit from the `EntitySynchronizer<TEntity, TSourceEntityEto>` class (just don't use the `Guid` generic argument in the previous example) and implement the `FindLocalEntityAsync` to find the entity in your local database using the `Repository`.
+
 `EntitySynchronizer` is compatible with the *Entity Versioning* system (see the [Entities document](Entities.md)). So, it works as expected even if the events are received as disordered. If the entity's version in your local database is newer than the entity in the received event, then the event is ignored. You should implement the `IHasEntityVersion` interface for the entity and ETO classes (for this example, you should implement for `Product`, `ProductEto` and `OrderProduct` classes).
 
 If you want to ignore some type of change events, you can set `IgnoreEntityCreatedEvent`, `IgnoreEntityUpdatedEvent` and `IgnoreEntityDeletedEvent` in the constructor of your class. Example: