refactor: 💡 model grants as a fragment-array for statefulness

addons/api/addon/models/fragment-string.js

@@ -0,0 +1,16 @@
+import Fragment from 'ember-data-model-fragments/fragment';
+import { attr } from '@ember-data/model';
+
+/**
+ * Represents an item in an array of strings.
+ */
+export default class FragmentStringModel extends Fragment {
+
+  // =attributes
+
+  @attr('string', {
+    description: 'The value of the string.'
+  })
+  value;
+
+}