Trait builder issue

trait-builder-issue.groovy

import groovy.xml.*

trait MyBuilder {
    def build2() {
        def mkp = new MarkupBuilder()
        
        mkp.foo {
            bar()
        }
    }
}

class Foo implements MyBuilder {

    def build1() {
        def mkp = new MarkupBuilder()
        
        mkp.foo {
            bar()
        }
    }
}

foo = new Foo()

foo.build1()
foo.build2()