These steps requires that the project has published before otherwise you have to follow this: https://central.sonatype.org/pages/producers.html

The Maven Travis setup in my open source project is based on: https://github.com/idealo/logback-redis/wiki/Release-Process that describes how to get rid of gpg key management and implement a trivial push-button release process with Github and TravisCI.

nexus repository manager

Links to Sonatype Jira and Nexus:
https://issues.sonatype.org
https://oss.sonatype.org/