How to enable async servlet support on Heroku?

How to enable async servlet support on Heroku?

java servlets heroku asynchronous servlet-3.0

heroku

How to retrieve image data send from iOS Swift through Alamofire on Heroku Servlet?

java ios servlets heroku

heroku

when deploying to heroku, it doesnt see my jar files or maven dependency in pom.xml

java maven servlets heroku

heroku