get error when use logout in the page genarated by Grails Spring Security Pluin

the error message is:

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    The specified HTTP method is not allowed for the requested resource.

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reason:
Grails Spring Security Plugin use GET request to logout, but its config set default logout request methord to POST for safety reason.

solution:
in Config.groovy, add:

grails.plugin.springsecurity.logout.postOnly = false

or, just use POST request to logout in your application, that's more safe.