Change AccessDecisionManager to UnanimousBased in Grails Spring Security Plugin

Change AccessDecisionManager to UnanimousBased in Grails Spring Security
Plugin

We're using the Grails spring security plugin:
http://grails.org/plugin/spring-security-core
I simply want to change the default access decision manager from the
default AffirmativeBased to UnanimousBased. I do not see it documented
anywhere in the plugin manual:
http://grails-plugins.github.io/grails-spring-security-core/docs/manual/
Does anyone know if it's possible to change this?
I added one additional voter, "myVoter" which is detected and working fine.
grails.plugins.springsecurity.voterNames = [
'myVoter', 'authenticatedVoter', 'roleVoter',
]