That's interesting, Tim. I have a brother whose actually good enough at this stuff to have a paid job with it. He's helping me and he thinks a Start.main is necessary. Is there any issue with Heroku, Spring Boot and/or Wicket that may be causing the confusion?
On reflection, that may be a Spring Boot main class. Spring Boot runs as a standard Java application that launches an internal Tomcat - or, in this case, jetty webserver. So while the webapp has no main class or method, Spring Boot may. But the best place to ask about Spring Boot is probably the Spring forum. Let me see if I can cross-link this thread there.
I'm going to be a "small government" candidate. I'll be the government. Just me. No one else.