Has-One Association in Model not working in Ext-js 5

Question

I have upgraded my application from Ext-js 4.2 to Ext-js 5.1.0

In the older version [Ext-js 4.2.1] we used to define Has-One Association in model as shown below.

Ext.define('application.model.buildingModel', {
extend: 'Ext.data.Model',
requires: [
    'Ext.data.field.String'
],
idProperty: 'uid',
fields: [
    {
        type: 'string',
        name: 'internalName'
    },
    {
        type: 'string',
        name: 'externalName'
    },
    {
        type: 'string',
        name: 'uid'
    },
    {
        type: 'string',
        name: 'status'
    },
    {
        name: 'address'
    }
],


hasOne: {
    model: 'application.model.addressModel',
    associationKey: 'address',
    foreignKey: 'address'
    getterName: 'getAddress',
    setterName: 'setAddress'
}
}); 

Since upgrading the application i am facing some issue with this.
I don't see address field present in record when seen by debugging.
When i fetch the record the address field is not present.
I think there are some changes needed in Ext-js 5 and I am new to Ext-js 5.

Can anyone help me in finding solution for this problem.

Thanks & Regards Sumanth K.P