Grails ClassNotFoundException: DefaultSecurityConfig running from IntelliJ

If you run into a “ClassNotFoundException: DefaultSecurityConfig” running Grails tests from IntelliJ IDEA, with the stacktrace below

java.lang.RuntimeException: java.lang.ClassNotFoundException: DefaultSecurityConfig
	at SpringSecurityCoreGrailsPlugin$_closure1.doCall(SpringSecurityCoreGrailsPlugin.groovy:151)
(... snip ...)
Caused by: java.lang.ClassNotFoundException: DefaultSecurityConfig
	... 61 more
| Error Error generating web.xml file

then try deleting the cached grails projects. For me the solution was to delete the projects in C:\Users\myuser\.grails\2.2.2\projects.
After that, the exception was gone.