Define abstract AsyncInitializedService class

Author: Julien Heller

src/types/AsyncInitializedService.ts

@@ -0,0 +1,12 @@
+/**
+ * Extend when declaring a service with asyncInitialization: true flag.
+ */
+export abstract class AsyncInitializedService {
+    public _initialized: Promise<any>;
+
+    constructor() {
+        this._initialized = this.initialize();
+    }
+
+    protected abstract initialize(): Promise<any>;
+}