I just copy pasted these changes from other repos (#47)

Author: Andrei-Predoiu

package.json

@@ -22,7 +22,9 @@
   },
   "dependencies": {
     "@backstage/catalog-model": "^0.8.2",
-    "@backstage/core": "^0.7.10",
+    "@backstage/core-app-api": "^0.1.10",
+    "@backstage/core-plugin-api": "^0.1.6",
+    "@backstage/core-components": "^0.3.3",
     "@backstage/plugin-catalog-react": "^0.2.5",
     "@material-ui/core": "^4.11.0",
     "react": "^16.13.1",

src/Router.tsx

@@ -1,5 +1,5 @@
 import { Entity } from "@backstage/catalog-model";
-import { MissingAnnotationEmptyState } from "@backstage/core";
+import { MissingAnnotationEmptyState } from "@backstage/core-components";
 import React from "react";
 import { Route, Routes } from "react-router";
 import { HarborDashboardPage } from "./components/HarborDashboardPage";

src/api/index.ts

@@ -1,4 +1,4 @@
-import { createApiRef, DiscoveryApi } from "@backstage/core";
+import { createApiRef, DiscoveryApi } from "@backstage/core-plugin-api";
 
 export interface harborApi {}
 

src/components/HarborDashboardPage.tsx

@@ -1,6 +1,6 @@
 import React from "react";
 import { Entity } from "@backstage/catalog-model";
-import { InfoCard } from "@backstage/core";
+import { InfoCard } from "@backstage/core-components";
 
 import { HarborRepository } from "./HarborRepository";
 import { useHarborAppData } from "./useHarborAppData";

src/components/HarborWidget.tsx

@@ -1,6 +1,6 @@
 import React from "react";
 import { Card, CardHeader } from "@material-ui/core";
-import { MissingAnnotationEmptyState } from "@backstage/core";
+import { MissingAnnotationEmptyState } from "@backstage/core-components";
 import { Entity } from "@backstage/catalog-model";
 import { HarborRepository } from "./HarborRepository";
 import {

src/plugin.ts

@@ -6,7 +6,7 @@ import {
   createRoutableExtension,
   createRouteRef,
   discoveryApiRef,
-} from "@backstage/core";
+} from "@backstage/core-plugin-api";
 
 import { HarborApiClient, harborApiRef } from "./api";
 import { HARBOR_ANNOTATION_REPOSITORY } from "./components/useHarborAppData";