With native saaj implementation to create soap message from this string :
<env:Envelope xmlns:env='http://schemas.xmlsoap.org/soap/envelope/'><S:Header xmlns:S='http://schemas.xmlsoap.org/soap/envelopes'></S:Header><S:Body xmlns:S='http://schemas.xmlsoap.org/soap/envelopes'> <ns1:addItemResponse xmlns:ns1='http://org.jboss.ws/addressing/replyto'> <result>Mars Bar</result> </ns1:addItemResponse> </S:Body></env:Envelope>

The created soap header and soap body are with prefix "env" . This caused some problem when ws security is enabled and soap header or body part is signed.