Deprecate ember-data adapter mixin

README.md

@@ -51,6 +51,9 @@ To use `ember-fetch` with TypeScript or enable editor's type support, You can ad
 ```
 
 ### Use with Ember Data
+
+> ember-data@3.9.2 was released with built-in fetch support, this mixin is no longer needed and will be removed in next major bump.
+
 To have Ember Data utilize `fetch` instead of jQuery.ajax to make calls to your backend, extend your project's `application` adapter with the `adapter-fetch` mixin.
 
 ```js

addon/mixins/adapter-fetch.ts

@@ -1,5 +1,6 @@
 import Mixin from '@ember/object/mixin';
 import { assign } from '@ember/polyfills';
+import { deprecate } from '@ember/debug';
 import RSVP, { reject } from 'rsvp';
 import fetch from 'fetch';
 import mungOptionsForFetch from '../utils/mung-options-for-fetch';
@@ -33,6 +34,7 @@ export function headersToObject(headers: Headers) {
 
 export interface FetchAdapter {
   headers: undefined | PlainHeaders;
+  init(): void;
   ajaxOptions(url: string, type: Method, options: object): FetchOptions;
   ajax(url: string, type: Method, options: object): RSVP.Promise<void>;
   _ajaxRequest(
@@ -60,6 +62,15 @@ export interface FetchAdapter {
 
 export default Mixin.create<FetchAdapter, DS.RESTAdapter>({
   headers: undefined,
+
+  init() {
+    this._super(...arguments);
+    deprecate('FetchAdapter is deprecated, it is no longer required for ember-data>=3.9.2', false, {
+      id: 'deprecate-fetch-ember-data-support',
+      until: '7.0.0'
+    });
+  },
+
   /**
    * @override
    */

tests/test-helper.js

@@ -2,7 +2,14 @@ import Application from '../app';
 import config from '../config/environment';
 import { setApplication } from '@ember/test-helpers';
 import { start } from 'ember-qunit';
+import { registerDeprecationHandler } from '@ember/debug';
 
 setApplication(Application.create(config.APP));
 
+registerDeprecationHandler((msg, options, next) => {
+  if (options.id !== 'deprecate-fetch-ember-data-support') {
+    next(msg, options);
+  }
+})
+
 start();

tsconfig.json

@@ -30,6 +30,7 @@
       "ember-fetch/*": ["addon/*"],
       "ember-fetch/test-support": ["addon-test-support"],
       "ember-fetch/test-support/*": ["addon-test-support/*"],
+      "@ember/debug": ["types/deprecate.d"],
       "*": ["types/*"]
     }
   },

types/deprecate.d.ts

@@ -0,0 +1,81 @@
+// TODO: This file should be removed once https://github.com/emberjs/ember.js/issues/17185 close
+
+// tslint:disable-next-line:strict-export-declare-modifiers
+interface DeprecationOptions {
+  id: string;
+  until: string;
+  url?: string;
+}
+
+/**
+ * Display a deprecation warning with the provided message and a stack trace
+ * (Chrome and Firefox only).
+ */
+export function deprecate(
+    message: string,
+    test: boolean,
+    options: DeprecationOptions
+): any;
+
+/**
+ * Alias an old, deprecated method with its new counterpart.
+ */
+export function deprecateFunc<Func extends ((...args: any[]) => any)>(
+    message: string,
+    options: DeprecationOptions,
+    func: Func
+): Func;
+
+// Type definitions for non-npm package @ember/debug 3.0
+// Project: https://emberjs.com/api/ember/3.4/modules/@ember%2Fdebug
+// Definitions by: Mike North <https://github.com/mike-north>
+// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+// TypeScript Version: 2.8
+
+/**
+ * Define an assertion that will throw an exception if the condition is not met.
+ */
+export function assert(desc: string, test?: boolean): void | never;
+/**
+ * Display a debug notice.
+ */
+export function debug(message: string): void;
+
+/**
+ * Convenience method to inspect an object. This method will attempt to
+ * convert the object into a useful string description.
+ */
+export function inspect(obj: any): string;
+/**
+ * Allows for runtime registration of handler functions that override the default deprecation behavior.
+ * Deprecations are invoked by calls to [Ember.deprecate](http://emberjs.com/api/classes/Ember.html#method_deprecate).
+ * The following example demonstrates its usage by registering a handler that throws an error if the
+ * message contains the word "should", otherwise defers to the default handler.
+ */
+export function registerDeprecationHandler(handler: (message: string, options: { id: string, until: string }, next: () => void) => void): void;
+/**
+ * Allows for runtime registration of handler functions that override the default warning behavior.
+ * Warnings are invoked by calls made to [Ember.warn](http://emberjs.com/api/classes/Ember.html#method_warn).
+ * The following example demonstrates its usage by registering a handler that does nothing overriding Ember's
+ * default warning behavior.
+ */
+export function registerWarnHandler(handler: (message: string, options: { id: string }, next: () => void) => void): void;
+
+/**
+ * Run a function meant for debugging.
+ */
+export function runInDebug(func: () => any): void;
+
+/**
+ * Display a warning with the provided message.
+ */
+export function warn(message: string, test: boolean, options: { id: string }): void;
+export function warn(message: string, options: { id: string }): void;
+/**
+ * @deprecated Missing deprecation options: https://emberjs.com/deprecations/v2.x/#toc_ember-debug-function-options
+ */
+export function warn(message: string, test: boolean, options?: { id?: string }): void;
+/**
+ * @deprecated Missing deprecation options: https://emberjs.com/deprecations/v2.x/#toc_ember-debug-function-options
+ */
+export function warn(message: string, options?: { id?: string }): void;