title: Spring REST, redirect request to another application with params (SSO, SAML)
body: <p>I must implement mechanism for SSO authentication based on SAML provider (in A app) and redirect to another application (B app) if the authentication is successeful. In the redirect I must include SAMLAssertion xml document (let's say encoded in base64) so I can authenticate in the another application (B app).</p>
  
  <p>A app is Spring boot application with simple form for credentials. On form submit there is a REST call to SAML Idp and resposne is consumed. If the response is successful I am executing redirect to B app. HERE I would like to include response from Idp.</p>
  
  <p>B app is complex Java application with own users database where I can implement custom authenticators based on HTTPServletRequests so I can consume both GET and POST requests. I would like to authenticate user in this app on the basis of saml resposne taken from A app. There are several reasons why B app cannot call IDp directly btw.</p>
  
  <p>How can I pass SAML resposne to B app?
  Is my approach correct in terms of SSO/SAML?</p>
  
  <p>I know there are several questions related to this, however I could not find any resolution for my specific case.</p>