运行 mvn help:system 后出现的问题，错误信息如下：

[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 17.008 s
[INFO] Finished at: 2018-08-10T14:22:12+08:00
[INFO] Final Memory: 6M/123M
[INFO] ------------------------------------------------------------------------
[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 (D:\maven\repository), central (https://repo.maven.apache.org/maven2)] -> [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]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/NoPluginFoundForPrefixException

我根据网上的一些资料，配置了 settings.xml 里的 mirrors 标签，试了很多个，都不行
我两台电脑上都出现了这个问题，Maven 3.5、3.3、3.2 都出现这个问题，环境是 JDK1.7 求助！！