Inverse relationships issue

ee.js

// app/models/product.js
export default DS.Model.extend({
  masterVariant: DS.belongsTo('product-variant'),
  variants: DS.hasMany('product-variant') // only contains the variants that are not master
});

// app/models/product-variant.js
export default DS.Model.extend({
  product: DS.belongsTo('product', { inverse: null }),
  master: DS.attr('boolean')
});