0.2 is a release. 1.0.RC1 is not. See https://jira.grails.org/browse/GPSPRINGSECURITYUI/?selectedTab=com.atlassian.jira.jira-projects-plugin:versions-panel. 

We only allow stable releases on libraries, plugins and frameworks, as per https://softeng.atlassian.net/wiki/display/QM/Software+development+guidelines.