Mapping map field to Ember Data

I have response from server in this format :

{
 "id":"552cd25444ae47fe5f3a41b2",
 "eventType":"REST_EVENT",
 "userSid":"REST_USER",
 "content":{
           "key":"value",
           "key1":"value1",
           "key2":"value2"
  }
}

How I can map content field to Ember Data Model if this field has dynamic count of values and without knowing key names ?