The dependency to the main extension is declared in the app.json file:
"id": "6d527590-711f-410c-b233-d267d192b13b","name": "SecondExtension","publisher": "DTacconi Inc.","version": "1.0.0.0","dependencies": [ { "appId": "15ecd2e5-b7a8-4612-ae6f-d722af29c0c0", "name": "MainExtension", "publisher": "DTacconi Inc.", "version": "1.0.0.0" }],
In the preceding code, we can see that the dependency must define four parameters: the application ID, name, publisher, and version. These are mandatory if we want to define a unique extension target.