I was tracing the jbossws SOAP messages with etherreal and found out that the responding soap messages do not have XML declarations.

SOAP messages normally have at lest for example <?xml version="1.0" encoding="UTF-8"?>.

The reason might be, that the method isWriteXMLDeclaration() in org.jboss.ws.soap.SOAPMessageImpl always returns false because the propValue in line

Object propValue = getProperty(WRITE_XML_DECLARATION);

is null.