anchor.diff:  
   When working with MongoDB, you can currently configure the following options using the API:
   
  -* association storage strategy (on the global, entity and property level)
  -* association document storage strategy (on the global, entity and property level)
  +* write concern
  +* association storage strategy
  +* association document storage strategy
   
   To set these options via the API, you need to create an +OptionConfigurator+ implementation
   as shown in the following example:
  
positive.code: [source, JAVA]
  ----
  @Entity
  @AssociationStorage(AssociationStorageType.ASSOCIATION_DOCUMENT)
  @AssociationDocumentStorage(AssociationDocumentType.COLLECTION_PER_ASSOCIATION)
  public class Zoo {
  
negative.code:     @Override
      public void configure(Configurable configurable) {
          configurable.configureOptionsFor( MongoDB.class )
              .writeConcern( WriteConcernType.REPLICA_ACKNOWLEDGED )
              .entity( Zoo.class )
                  .associationStorage( AssociationStorageType.ASSOCIATION_DOCUMENT )
                  .associationDocumentStorage( AssociationDocumentType.COLLECTION_PER_ASSOCIATION )
                  .property( "animals", ElementType.FIELD )
                      .associationStorage( AssociationStorageType.IN_ENTITY )
              .entity( Animal.class )
                  .writeConcern( new RequiringReplicaCountOf( 3 ) )
                  .associationStorage( AssociationStorageType.ASSOCIATION_DOCUMENT );
      }
  }
  