mvn help:system报错 No plugin

[ERROR] No plugin found for prefix 'help' in the current project and in the plugin groups [org.apache.maven.plugins, org.codehaus.mojo] available from the repositories [local (C:\Users\admin.m2\repository), centralMirror (http://localhost/nexus/content/groups/public/)] -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]

http://blog.csdn.net/gaoshang10/article/details/20454723