Refine the viewer when be visible. (#50)

Author: yaohaizh

package.json

@@ -76,7 +76,8 @@
       "explorer": [
         {
           "id": "javaDependencyExplorer",
-          "name": "Java Dependencies"
+          "name": "Java Dependencies",
+          "when": "extensionActivated"
         }
       ]
     }

src/extension.ts

@@ -11,6 +11,9 @@ import { DependencyExplorer } from "./views/depedencyExplorer";
 
 export function activate(context: ExtensionContext) {
     Telemetry.sendEvent("activateExtension", {});
+
+    commands.executeCommand("setContext", "extensionActivated", true);
+
     Services.initialize(context);
     Settings.initialize(context);