HTTPS alters incoming soap messages using SpringWS

Issue

We're exposing some web services via Spring WS framework. Those WS work correctly when called on http protocol.
But when called on https the calls fail with message:

com.sun.xml.messaging.saaj.SOAPExceptionImpl: Unable to create envelope from given source: 
    com.sun.xml.messaging.saaj.soap.EnvelopeFactory.createEnvelope(EnvelopeFactory.java:127)
    com.sun.xml.messaging.saaj.soap.ver1_1.SOAPPart1_1Impl.createEnvelopeFromSource(SOAPPart1_1Impl.java:83)
    com.sun.xml.messaging.saaj.soap.SOAPPartImpl.getEnvelope(SOAPPartImpl.java:143)
    org.springframework.ws.soap.saaj.support.SaajUtils.getSaajVersion(SaajUtils.java:155)
    org.springframework.ws.soap.saaj.SaajSoapMessage.getSaajVersion(SaajSoapMessage.java:257)
    org.springframework.ws.soap.saaj.SaajSoapMessage.getImplementation(SaajSoapMessage.java:342)
    org.springframework.ws.soap.saaj.SaajSoapMessage.<init>(SaajSoapMessage.java:117)
    org.springframework.ws.soap.saaj.SaajSoapMessageFactory.createWebServiceMessage(SaajSoapMessageFactory.java:184)
    org.springframework.ws.soap.saaj.SaajSoapMessageFactory.createWebServiceMessage(SaajSoapMessageFactory.java:58)
    org.springframework.ws.transport.AbstractWebServiceConnection.receive(AbstractWebServiceConnection.java:90)
    org.springframework.ws.transport.support.WebServiceMessageReceiverObjectSupport.handleConnection(WebServiceMessageReceiverObjectSupport.java:86)
    org.springframework.ws.transport.http.WebServiceMessageReceiverHandlerAdapter.handle(WebServiceMessageReceiverHandlerAdapter.java:57)
    org.springframework.ws.transport.http.MessageDispatcherServlet.doService(MessageDispatcherServlet.java:221)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:669)
    org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:585)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:754)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
root cause javax.xml.transform.TransformerException: org.xml.sax.SAXParseException; lineNumber: 1; columnNumber: 2; The markup in the document preceding the root element must be well-formed.
    org.apache.xalan.transformer.TransformerIdentityImpl.transform(TransformerIdentityImpl.java:502)
    com.sun.xml.messaging.saaj.util.transform.EfficientStreamingTransformer.transform(EfficientStreamingTransformer.java:414)
    com.sun.xml.messaging.saaj.soap.EnvelopeFactory.createEnvelope(EnvelopeFactory.java:118)
    com.sun.xml.messaging.saaj.soap.ver1_1.SOAPPart1_1Impl.createEnvelopeFromSource(SOAPPart1_1Impl.java:83)
    com.sun.xml.messaging.saaj.soap.SOAPPartImpl.getEnvelope(SOAPPartImpl.java:143)
    org.springframework.ws.soap.saaj.support.SaajUtils.getSaajVersion(SaajUtils.java:155)
    org.springframework.ws.soap.saaj.SaajSoapMessage.getSaajVersion(SaajSoapMessage.java:257)
    org.springframework.ws.soap.saaj.SaajSoapMessage.getImplementation(SaajSoapMessage.java:342)
    org.springframework.ws.soap.saaj.SaajSoapMessage.<init>(SaajSoapMessage.java:117)
    org.springframework.ws.soap.saaj.SaajSoapMessageFactory.createWebServiceMessage(SaajSoapMessageFactory.java:184)
    org.springframework.ws.soap.saaj.SaajSoapMessageFactory.createWebServiceMessage(SaajSoapMessageFactory.java:58)
    org.springframework.ws.transport.AbstractWebServiceConnection.receive(AbstractWebServiceConnection.java:90)
    org.springframework.ws.transport.support.WebServiceMessageReceiverObjectSupport.handleConnection(WebServiceMessageReceiverObjectSupport.java:86)
    org.springframework.ws.transport.http.WebServiceMessageReceiverHandlerAdapter.handle(WebServiceMessageReceiverHandlerAdapter.java:57)
    org.springframework.ws.transport.http.MessageDispatcherServlet.doService(MessageDispatcherServlet.java:221)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:669)
    org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:585)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:754)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
root cause org.xml.sax.SAXParseException; lineNumber: 1; columnNumber: 2; The markup in the document preceding the root element must be well-formed.
    org.apache.xerces.parsers.AbstractSAXParser.parse(Unknown Source)
    org.apache.xerces.jaxp.SAXParserImpl$JAXPSAXParser.parse(Unknown Source)
    org.xml.sax.helpers.XMLFilterImpl.parse(XMLFilterImpl.java:357)
    org.apache.xalan.transformer.TransformerIdentityImpl.transform(TransformerIdentityImpl.java:485)
    com.sun.xml.messaging.saaj.util.transform.EfficientStreamingTransformer.transform(EfficientStreamingTransformer.java:414)
    com.sun.xml.messaging.saaj.soap.EnvelopeFactory.createEnvelope(EnvelopeFactory.java:118)
    com.sun.xml.messaging.saaj.soap.ver1_1.SOAPPart1_1Impl.createEnvelopeFromSource(SOAPPart1_1Impl.java:83)
    com.sun.xml.messaging.saaj.soap.SOAPPartImpl.getEnvelope(SOAPPartImpl.java:143)
    org.springframework.ws.soap.saaj.support.SaajUtils.getSaajVersion(SaajUtils.java:155)
    org.springframework.ws.soap.saaj.SaajSoapMessage.getSaajVersion(SaajSoapMessage.java:257)
    org.springframework.ws.soap.saaj.SaajSoapMessage.getImplementation(SaajSoapMessage.java:342)
    org.springframework.ws.soap.saaj.SaajSoapMessage.<init>(SaajSoapMessage.java:117)
    org.springframework.ws.soap.saaj.SaajSoapMessageFactory.createWebServiceMessage(SaajSoapMessageFactory.java:184)
    org.springframework.ws.soap.saaj.SaajSoapMessageFactory.createWebServiceMessage(SaajSoapMessageFactory.java:58)
    org.springframework.ws.transport.AbstractWebServiceConnection.receive(AbstractWebServiceConnection.java:90)
    org.springframework.ws.transport.support.WebServiceMessageReceiverObjectSupport.handleConnection(WebServiceMessageReceiverObjectSupport.java:86)
    org.springframework.ws.transport.http.WebServiceMessageReceiverHandlerAdapter.handle(WebServiceMessageReceiverHandlerAdapter.java:57)
    org.springframework.ws.transport.http.MessageDispatcherServlet.doService(MessageDispatcherServlet.java:221)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:669)
    org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:585)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:754)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:847)