According to the osmdroid API documentation is necessary to define a user-agent. See: https://github.com/osmdroid/osmdroid/wiki/Important-notes-on-using-osmdroid-in-your-app
Set the HTTP User-Agent variable
This setting identifies your app uniquely to tile servers. It's not the end user's identity, but the name of your app. If your users abuse the tile server or your app does in some way, this will prevent everyone that uses osmdroid from getting banned rather than just the users of your app. org.osmdroid.tileprovider.constants.OpenStreetMapTileProviderConstants#setUserAgentValue>
But I was not sure if there is a convention to set the user-agent based on a pattern. I should just set the name of my application? The application package name? Or what? Does anyone have any ideas?
Yes, usually you should set the (preferably) unique name of your application. Contrary to its name the HTTP user agent represents the software and not the actual user.