To logout an user from the SP an LogoutRequest is sent. The data needed about the user is the SessionIndex and NameID from the data recived at login. I my case in the Assertion in the Artifact Resolve Response.

//IPR Ergogroup ASpublic static void doSynchronousLogout(final HttpSession sessionToLogout, final SAMLMetaData metaData) throws SOAPException, SecurityException, ValidationException, IllegalArgumentException, java.lang.SecurityException, IllegalAccessException, MarshallingException, SignatureException {  NameID nameId = (NameID)sessionToLogout.getAttribute("SAMLNameID");  String sessionIndex = (String)sessionToLogout.getAttribute("SAMLSessionIndex");     Body body = buildSAMLObjectWithDefaultName(Body.class);   LogoutRequest logoutRequest = genererateLogoutRequest(nameId, sessionIndex, metaData);   signLogoutRequest(logoutRequest);   body.getUnknownXMLObjects().add(logoutRequest);   nameId.detach();   Envelope envelope = buildSAMLObjectWithDefaultName(Envelope.class);   envelope.setBody(body);   SAMLUtil.logSAMLObject(envelope);   BasicSOAPMessageContext soapContext = new BasicSOAPMessageContext();   soapContext.setOutboundMessage(envelope);   HttpClientBuilder clientBuilder = new HttpClientBuilder();   HttpSOAPClient soapClient = new HttpSOAPClient(clientBuilder.buildClient(), new BasicParserPool());    String sloServiceURL = null;    for (SingleLogoutService sls : metaData.getIdpEntityDescriptor().getIDPSSODescriptor(SAMLConstants.SAML20P_NS).getSingleLogoutServices()) {     if (sls.getBinding().equals(SAMLConstants.SAML2_SOAP11_BINDING_URI)) {      sloServiceURL = sls.getLocation();     }    }    soapClient.send(sloServiceURL, soapContext);    Envelope soapResponse = (Envelope)soapContext.getInboundMessage();    SAMLUtil.logSAMLObject(soapResponse);    validateSLOResponse(soapResponse, logoutRequest.getID());    verifySLOResponseSignature(soapResponse);    processSLOResponse(soapResponse);   }  private static LogoutRequest genererateLogoutRequest(final NameID nameId, final String sessionIndex, final SAMLMetaData metaData) throws IllegalArgumentException, java.lang.SecurityException, IllegalAccessException {  LogoutRequest logoutRequest = buildSAMLObjectWithDefaultName(LogoutRequest.class);  logoutRequest.setID(SAMLUtil.getSecureRandomIdentifier());  for (SingleLogoutService sls : metaData.getIdpEntityDescriptor().getIDPSSODescriptor(SAMLConstants.SAML20P_NS).getSingleLogoutServices()) {   if (sls.getBinding().equals(SAMLConstants.SAML2_SOAP11_BINDING_URI)) {    logoutRequest.setDestination(sls.getLocation());   }  }  logoutRequest.setIssueInstant(new DateTime());  Issuer issuer = buildSAMLObjectWithDefaultName(Issuer.class);  issuer.setValue(EvoteProperties.getProperty("SPEntityId"));  logoutRequest.setIssuer(issuer);  SessionIndex sessionIndexElement = buildSAMLObjectWithDefaultName(SessionIndex.class);  sessionIndexElement.setSessionIndex(sessionIndex);  logoutRequest.getSessionIndexes().add(sessionIndexElement);  logoutRequest.setNameID(nameId);  return logoutRequest; }

LogoutRequest sent:

my-aliasSn7qX8Yf4Pcs6SLl4Yn0NyEx6P0=cE3wgjeM+45uk/XVNQl+1NZKeRwRzFnJN9xaL/36vnXqu6eLBqs8eqdQ2a+yY9UkZz0gU1NrTqUMQgIANw1WfkL2a+sxQqqu2p4ggXKNwHiMWbyfPEUkxQM4wSwr3ECObjyVqrgPDA+4TiDyqPj2NBtZGo8WU3fvpOGQkQN19f0=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

This is the resulting LogoutResponse in my case:

idp-aliasCDFFLlD2FX8fjlPJLKpJZRusnx0=cKgVEfLR48x7urpH+TV+V1gHYnVhc/ErkMhwp17rjAMfjHKHk0EPgH2+aOV7Z83udbfr0RPKF5ZdMg0zq1KIm29RsqUsUYNKKNiYPlEkBIoHPcc2AhftpA/VNRjea7q2W9+y6XV2YWjzGnArrfflv1KM1t5C89Vz/VB0jQdJvMU=Request is done successfully