Groovy XML MarkupBuilder does not create root <?xml .... ?>

Question

I am using XML MarkupBuilder to generate XML files

import groovy.xml.StreamingMarkupBuilder
import groovy.xml.MarkupBuilder
import org.custommonkey.xmlunit.*

....

def xmlObj = new StringWriter()
def xml = new MarkupBuilder(xmlObj)
xml.book("id":21){
    name('bookname')
}

and I get the output:

<book id='21'>
    <name>bookname</name>
</book>

how can I make it generate the root xml tag as well?

<?xml version="1.0" encoding="utf-8"?>

Answer 1

You need to add it yourlsef

def xml = new StreamingMarkupBuilder().bind{
        mkp.xmlDeclaration()
        task {
            id(_Id)
            name("clean")
        }
    }

Answer 2

You can add xml declaration with MarkupBuilder too:

def xml = new MarkupBuilder(xmlObj)
xml.mkp.xmlDeclaration(version: "1.0", encoding: "utf-8")
xml.book("id":21){
    name('bookname')
}