Place store on Ember.Route to maintain default store behaviour

.eslintrc.js

@@ -79,6 +79,7 @@ module.exports = {
     WeakMap: true,
     Set: true,
     Promise: false,
+    Symbol: true,
   },
   env: {
     browser: true,

packages/-ember-data/addon/setup-container.js

@@ -1,6 +1,10 @@
+import { getOwner } from '@ember/application';
 import { deprecate } from '@ember/debug';
+import Route from '@ember/routing/route';
 import { DEBUG } from '@glimmer/env';
 
+const EMBER_DATA_STORE = Symbol('ember-data-store');
+
 import Store from '@ember-data/store';
 
 function initializeStore(application) {
@@ -46,6 +50,36 @@ function initializeStore(application) {
   }
 }
 
+// Implicit injection was removed. This is a replacement for Ember Route implicit store for >= v4.0
+Route.reopen({
+  get store() {
+    if (this[EMBER_DATA_STORE]) {
+      return this[EMBER_DATA_STORE];
+    }
+
+    const store = getOwner(this).lookup('service:store');
+    this[EMBER_DATA_STORE] = store;
+
+    deprecate(
+      'In 4.0, ember and ember-data removed implicitly injecting the store on all Ember framework objects. However, Ember.Route still needs to support a default store and it looks like you do not have an explicit `@service store` on your Route. Please add this service injection to your Route.',
+      false,
+      {
+        id: 'ember-data:implicit-store-on-route',
+        until: '5.0',
+        since: {
+          available: '4.0',
+          enabled: '4.0',
+        },
+      }
+    );
+
+    return store;
+  },
+  set store(value) {
+    this[EMBER_DATA_STORE] = value;
+  },
+});
+
 export default function setupContainer(application) {
   initializeStore(application);
 }