Parameter 'requires' is already set on File[/tmp/one] by one at /home/rip/test1.pp:9; cannot redefine at /home/rip/test1.pp:17 on node dev2

class files {
        @file{["/tmp/one", "/tmp/two", "/tmp/three"]:
                content => "foo"
        }
}

class one inherits files {
        File["/tmp/one"]{
                requires +> File["/tmp/two"]
        }

        realize(File["/tmp/one"])
}

class two inherits files {
        File["/tmp/one"]{
                requires +> File["/tmp/three"]
        }

        realize(File["/tmp/two"])
}

class three inherits files {
        realize(File["/tmp/three"])
}

include files
include one
include two