fix: Delete complex field values if empty

app/serializers/session.js

@@ -0,0 +1,18 @@
+import ApplicationSerializer from 'open-event-frontend/serializers/application';
+import CustomPrimaryKeyMixin from 'open-event-frontend/mixins/custom-primary-key';
+
+export default ApplicationSerializer.extend(CustomPrimaryKeyMixin, {
+
+  serialize() {
+    const json = this._super(...arguments);
+
+    const { attributes } = json.data;
+    if (Object.keys(attributes['complex-field-values']).length === 0) {
+      // If object is empty, remove it so that validations on server aren't triggered
+      delete attributes['complex-field-values'];
+    }
+
+    return json;
+  }
+
+});