In your pom.xml, under build → plugins → plugin(maven-confluence-plugin) → configuration → instructions, do you have this?
<Atlassian-Plugin-Key>${atlassian.plugin.key}</Atlassian-Plugin-Key>
In your pom.xml, under build → plugins → plugin(maven-confluence-plugin) → configuration → instructions, do you have this?
<Atlassian-Plugin-Key>${atlassian.plugin.key}</Atlassian-Plugin-Key>