anchor.diff:  
   When creating related items using nesting the foreign key columns connecting master-child tables will be filled automatically, so in this case there is no need to specify in message instance a back link to the wrapping user instance via 'user' field on the message.
   
  -Also notice how we 'room' within a message we only specify a 'self' / 'href' field. This is called a _resource reference_. Table 'messages' has a many-to-one relationship with 'rooms', which means that 'messages' table contains a foreign key column 'room_id' that links to table 'rooms'.
  -
  -Currently creating instances related via many-to-one relationship is not supported. Support for this may be added in the future.
  +Also notice how in 'room' within a message we only specify a 'self' / 'href' field. This is called a _resource reference_. Table 'messages' has a many-to-one relationship with 'rooms', which means that 'messages' table contains a foreign key column 'room_id' that links to table 'rooms'.
  +
  +Currently creating nested instances related via many-to-one relationship is not supported. Support for this may be added in the future.
   
   == Updating records (items)
   
  
positive.code:     EOF
  
  
  One-to-many child items can be included as full state child items into the wrapping item, and they will be created.
  
  It is up to a caller to ensure that any dependencies of each item are fulfilled by the time it's that item's turn to be processed.
  
  In the above example we first create a new user, then create a new room that refers to just created user, and finally we create a message that refers to both user, and room that were just created.
  
  If ordering of these three items was any different there would be dependency errors during processing.
  
  
negative.code:       "rooms" : [ ]
      }
  
  In this case we assume there are two additional tables present in our database with foreign key constraint referencing the 'users' table. The ids of those tables are used to name a 'synthetic' collection fields 'messages', and 'rooms'. This is how one-to-many relationships are automatically resolved.
  
  Since this item was only just created it can't possibly have any references pointing to it yet, therefore these two fields are empty.
  
  