import groovy.xml.MarkupBuilder

def writer = new StringWriter()
def xml = new MarkupBuilder(writer)
xml.example() {
        person(name: 'hoge', type: 'hage'){
                city('Tokyo')
                remarks('特に無し')
        }
        person(name: 'moge', type: 'debu', foo: 'bar'){
                city('Saitama')
                remarks('だ埼玉って言わないで')
        }
}
def doc = new XmlSlurper().parseText(writer.toString())
println "city=${doc.person.find { it.@type == 'debu' }.city}"

出力結果：

city=Saitama