How to remove xml declaration from request body

[lospejos]

I need to build a request without xml declaration.
Using example code from main wslite page, I got SOAP request body:

POST /Holidays/US/Dates/USHolidayDates.asmx HTTP/1.1
Content-Type: text/xml; charset=UTF-8
SOAPAction: http://www.27seconds.com/Holidays/US/Dates/GetMothersDay
Connection: Close
Accept-Encoding: gzip
Cache-Control: no-cache
Pragma: no-cache
User-Agent: Java/1.8.0_172
Host: www.holidaywebservice.com
Accept: text/html, image/gif, image/jpeg, *; q=.2, */*; q=.2
Content-Length: 314

<?xml version='1.0' encoding='UTF-8'?>
<soap-env:Envelope xmlns:soap-env='http://schemas.xmlsoap.org/soap/envelope/'>
  <soap-env:Header />
  <soap-env:Body>
    <GetMothersDay xmlns='http://www.27seconds.com/Holidays/US/Dates/'>
      <year>2011</year>
    </GetMothersDay>
  </soap-env:Body>
</soap-env:Envelope>

I need to build a request without xml declaration in its body. Is it real to do using DSL style (I know I can pass the raw string as request body but searching for more high level approach)? Could you give an example?
Thanks