I solved it as follows (possibly already answered but here are my steps)
$ heroku local web
Got the following output in the console
forego | starting web.1 on port 5000
web.1 | /bin/bash: target/bin/Service: Permission denied
Then I did
$chmod 777 target/bin/Service
and problem resolved.
Here, Service is the name of my application (as specified in pom.xml org.codehaus.mojo plugin) and here is what my Procfile file content looks like
web: target/bin/Service -Dhttp.port=${PORT} ${JAVA_OPTS} -DapplyEvolutions.default=true -Ddb.default.driver=org.postgresql.Driver -Ddb.default.url=${DATABASE_URL}