To add a namespace prefix to all tags, you must update the desired prefix (and ultimately the namespace) in each child inserted, otherwise it will inherit the namespace (implicitly) from the parent element.
Try for example:
SOAPBodyElement getList = body.addBodyElement(bodyName, "v9", "http://URL TO SERVER");
or
soapBody.addChildElement("SomeElement", "v9", "http://URL TO SERVER");
or
soapBody.addChildElement("v9:SomeElement");
QName String Name.
SOAP-API/, : redeclare (), ().