• Use pressgang at least 3.1.3
• Maven configuration to inspire (not sure how that translates in gradle): https://github.com/pressgang/pressgang-tools/blob/master/pressgang-tools-example/pom.xml#L43
• Specific this part:

                <!-- To use Google Analytics: -->
                <transformerParameters>
                  <html.googleAnalyticsId>UA-XXXXXXX-X</html.googleAnalyticsId>
                  <html.googleTagManagerId>GTM-NJWS5L</html.googleTagManagerId>
                  <html.googleTagManagerChannel>PressgangToolsExample</html.googleTagManagerChannel>
                </transformerParameters>
  

And then you'll find a bit of a GA code near the bottom of your html files.

The Google GA script itself is smart enough to not call home if used from a file:// address.
If a company ends up hosting it on their own server, I believe you can easily filter out those calls in GA adminstration views.