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: 
  The call to +configureOptionsFor()+, passing the store-specific identifier type +MongoDB+,
  provides the entry point into the API. Following the fluent API pattern, you then can configure
  global options and navigate to single entities or properties to apply options specific to these.
  
  Options given on the property level precede entity-level options. So e.g. the +animals+ association of the +Zoo+
  class would be stored using the in-entity strategy, while all other associations of the +Zoo+ entity would
  
negative.code: ===== Annotation based configuration
  
  Hibernate OGM allows to configure store-specific options via Java annotations.
  When working with the MongoDB backend, you can specify the following settings:
  
  * the write concern for entities and associations using the +@WriteConcern+ annotation
  * a strategy for storing associations using the +@AssociationStorage+ and +@AssociationDocumentStorage+ annotations
  (refer to <<ogm-mongodb-storage-prinicples>> to learn more about these options).
  
  The following shows an example:
  