Can you help in solving Error R10 Boot Timeout, not binding to port?

A few of us are working on this problem and have searched for hours to solve this problem. Currently my Procfile looks like this:

web: java $JAVA_OPTS -jar target/GeodeTwitter2-0.0.1-SNAPSHOT.jar -Dserver.port=$PORT

We're building a Twitter bot to tweet from a static file. It works for 90 seconds then stops. Here's an example of the error log:

2019-05-16T13:39:27.118323+00:00 heroku[web.1]: State changed from starting to crashed 2019-05-16T13:39:26.969000+00:00 heroku[web.1]: Error R10 (Boot timeout) -> Web process failed to bind to $PORT within 90 seconds of launch 2019-05-16T13:39:26.969118+00:00 heroku[web.1]: Stopping process with SIGKILL 2019-05-16T13:39:27.091840+00:00 heroku[web.1]: Process exited with status 137

We're using Spring Boot with Maven. When run locally from Spring Boot, the app works and tweets indefinitely. Please let me know any other information that I should provide.