Change effective on 14 October 2019
Heroku’s Java support has upgraded the default version of Maven to 3.6.2. To force this version, create a
system.properties file in the root of your application (or modify the existing file) and add this line:
You may also select 3.3.9 (the previous default). If you are already using an older version of Maven, you will not be upgraded to the new version by default. You must specify the version in
system.properties to receive the upgrade.