Change effective on 04 October 2018
Heroku’s support for Java, Scala, Clojure, and Gradle has been updated to use new default options based on dyno size and JDK version. When using JDK 10 or 11, the option
-XX:+UseContainerSupport will be automatically set in the
JAVA_TOOL_OPTIONS environment variable. Other options based on dyno size have also changed. For more information on these changes and how to override them, see the Dev Center documentation on Heroku’s Java support.