XRM Web Api (create record) - issues creating a note (annotation) with an object ID specified

I've been looking to add a feature where using client side script, we would like to create a note (annotation).  I've been able to create a note but haven't been able to assign it to a custom entity.  Here is the client side code we're using:

var clientID = formContext.getAttribute("client").getValue()[0].id;

        // define the data to create new annotation
        var data =
            {
                "subject": "Client Interaction","notetext": "Client Interaction logged","isdocument": false,"objectid":
                {"logicalname": "custom_client","custom_clientid": clientID
                }
            }

        // create annotation (note) record
        Xrm.WebApi.createRecord("annotation", data).then(
            function success(result) {
                console.log("Note created with ID: " + result.id);
                // perform operations on record creation
            },
            function (error) {
                console.log(error.message);
                // handle error conditions
            }
        );

I'm successfully able to create the annotation (note) if I remove the objectid property but we really want to create the note so it's regarding (linked) to the custom entity client.  The error we see in the console is:

An error occurred while validating input parameters: Microsoft.OData.ODataException: Does not support untyped value in non-open type.

Any help would be greatly appreciated!