Moved reporting plugins to <reporting> element since the new Configuration (Maven 3 only, no reports configuration inheritance). Starting with maven-site-plugin 3.0, reports could be configured in the configuration of maven-site-plugin as <reportPlugins> elements. This new configuration format is not actually ready for end-users: please don't use it for the moment. As a consequence, with maven-site-plugin 3.3, the <reportPlugins> configuration has simply been removed (more precisely marked private/internal), since it should not be used directly.
See http://maven.apache.org/plugins/maven-site-plugin/maven-3.html for more information.