Associations in JSON responses are, by default, expressed as a JSONArray. You can control the format of 1-1 associations in JSON responses by setting the property: 
com.corticon.server.execution.json.association.singleton=JSONObject
in the brms.properties on the machine where the JSON requests are processed. When this property is set, and when a Rule alters a 1-1 association through an = (equals) operator, the entity being assigned to the association will be expressed as a JSONObject, rather than an entity inside a JSONArray in the JSON response. This property will not unconditionally change 1-1 Associations from a JSONArray to a JSONObject in the JSON response. Changing from a JSONArray to a JSONObject will only occur when a Rule fires to alter the contents of an Association.