Associations aren't modified by calling setters on the object and then calling modify. Associations are changed with explicit API calls. Examples include, serverPoolAddServer, networkAddEthernetPort, etc.

Associations are changed in one direction only - typically from the "parent". Using the above cases, you add servers to a server pool, you don't set the serverPoolId on a server, even though it appears as a property of the server object. See Section 5.1.3, “Read-only Methods and Object Properties” for more information on these properties and why they exist for any object.

As mentioned previously in Section 5.1.1, “Object Modification”, the IDs of objects that have an association with a "parent" object cannot be modified even if there are methods that seem like they might achieve this for you. These associated object IDs that appear as properties of a "parent" object are not modifiable directly and are automatically associated when an association method is called from the API.