Deprecate owner.inject

packages/@ember/-internals/container/lib/registry.ts

@@ -1,6 +1,6 @@
 import { Factory } from '@ember/-internals/owner';
 import { dictionary, intern } from '@ember/-internals/utils';
-import { assert } from '@ember/debug';
+import { assert, deprecate } from '@ember/debug';
 import { DEBUG } from '@glimmer/env';
 import Container, { ContainerOptions, LazyInjection } from './container';
 
@@ -566,6 +566,20 @@ export default class Registry implements IRegistry {
       this.isValidFullName(injectionName)
     );
 
+    deprecate(
+      `owner.inject has been deprecated and will be removed in v5.0.0. Please refactor to explicitly instantiate ${property} on ${fullName}`,
+      false,
+      {
+        id: 'remove-owner-inject',
+        until: '5.0.0',
+        url: 'TODO',
+        for: 'ember-source',
+        since: {
+          enabled: '4.0.0',
+        },
+      }
+    );
+
     let normalizedInjectionName = this.normalize(injectionName);
 
     if (fullName.indexOf(':') === -1) {

packages/@ember/application/lib/application.js

@@ -1038,8 +1038,6 @@ const Application = Engine.extend({
       } else { // node
         application.register('service:network', NodeNetworkService);
       }
-
-      application.inject('route', 'network', 'service:network');
     };
 
     export default {
@@ -1050,13 +1048,16 @@ const Application = Engine.extend({
 
     ```app/routes/post.js
     import Route from '@ember/routing/route';
+    import { inject as service } from '@ember/service';
 
     // An example of how the (hypothetical) service is used in routes.
 
-    export default Route.extend({
+    export default class IndexRoute extends Route {
+      @service network;
+
       model(params) {
         return this.network.fetch(`/api/posts/${params.post_id}.json`);
-      },
+      }
 
       afterModel(post) {
         if (post.isExternalContent) {
@@ -1065,7 +1066,7 @@ const Application = Engine.extend({
           return post;
         }
       }
-    });
+    }
     ```
 
     ```javascript