java.lang.IllegalArgumentException: The main resource set specified [...] is not valid

Seems like you have an outdated web application referenced in your Tomcat embeded server (You are using Tomcat As within Eclipse right?).

First checkout the deployed application within you server, and check the artifact name j2eeapplication-0.0.1-SNAPSHOT and version. You may need to remove it and clean your working directory the redeploy it and you should be safe.