[BUGFIX] Fix #18268 query param options not being read

packages/@ember/-internals/routing/lib/system/route.ts

@@ -495,7 +495,14 @@ class Route extends EmberObject.extend(ActionHandler, Evented) implements IRoute
     @property _optionsForQueryParam
   */
   _optionsForQueryParam(qp: QueryParam) {
-    return get(this, `queryParams.${qp.urlKey}`) || get(this, `queryParams.${qp.prop}`) || {};
+    const queryParams = get(this, 'queryParams');
+    return (
+      get(queryParams, qp.urlKey) ||
+      get(queryParams, qp.prop) ||
+      queryParams[qp.urlKey] ||
+      queryParams[qp.prop] ||
+      {}
+    );
   }
 
   /**

packages/@ember/-internals/routing/tests/system/route_test.js

@@ -132,6 +132,37 @@ moduleFor(
       runDestroy(owner);
     }
 
+    ['@test _optionsForQueryParam should work with nested properties'](assert) {
+      let route = EmberRoute.extend({
+        queryParams: {
+          'nested.foo': {
+            // By default, controller query param properties don't
+            // cause a full transition when they are changed, but
+            // rather only cause the URL to update. Setting
+            // `refreshModel` to true will cause an "in-place"
+            // transition to occur, whereby the model hooks for
+            // this route (and any child routes) will re-fire, allowing
+            // you to reload models (e.g., from the server) using the
+            // updated query param values.
+            refreshModel: true,
+
+            // By default, the query param URL key is the same name as
+            // the controller property name. Use `as` to specify a
+            // different URL key.
+            as: 'foobar',
+          },
+        },
+      }).create();
+
+      assert.strictEqual(
+        route._optionsForQueryParam({
+          prop: 'nested.foo',
+          urlKey: 'foobar',
+        }),
+        route.queryParams['nested.foo']
+      );
+    }
+
     ["@test modelFor doesn't require the routerMicrolib"](assert) {
       let route = EmberRoute.create({
         _router: { _routerMicrolib: null },