travis-settings.xml

<?xml version="1.0" encoding="UTF-8"?>
<settings>
  <servers>
        <server>
            <!-- Maven Central Deployment -->
            <id>ossrh</id>
            <username>${env.SONATYPE_USERNAME}</username>
            <password>${env.SONATYPE_PASSWORD}</password>
        </server>
    </servers>
</settings>