gistfile1.txt

role defined previously 

User.createCriteria().list(){ 
  createAlias( 'userRole', 'ur' )
  and{ 
    eq( 'role', 'ur.role' )
    eq( 'ur.role', role )
  }
  projections{
    property("username")
  } 
}

This unfortunately doesn't work because User doesn't have a hasMany relationship to UserRole, UserRole just has a User. This is with the spring security plugin, so the domain classes look basically like the ones in the spring security core plugin here: https://github.com/grails-plugins/grails-spring-security-core/tree/master/grails-app/domain/test