AuthNRequest#Destination contains the SP entity ID, not the IDP SSO URI

[fhanik]

Currently: (Incorrect Destination)

<saml2p:AuthnRequest 
    Destination="http://localhost:8080/login/saml2/sso/simplesamlphp"
    ForceAuthn="false" ID="ARQ28ad7a9-931d-41e6-bb94-785b3279c11f" IsPassive="false"
    IssueInstant="2019-09-29T22:26:17.265Z"
    ProtocolBinding="urn:oasis:names:tc:SAML:2.0:bindings:HTTP-Redirect" Version="2.0"
    xmlns:saml2p="urn:oasis:names:tc:SAML:2.0:protocol">

Should be: (Correct Destination)

<saml2p:AuthnRequest 
    Destination="https://simplesaml-for-spring-saml.cfapps.io/saml2/idp/SSOService.php"
    ForceAuthn="false" ID="ARQ28ad7a9-931d-41e6-bb94-785b3279c11f" IsPassive="false"
    IssueInstant="2019-09-29T22:26:17.265Z"
    ProtocolBinding="urn:oasis:names:tc:SAML:2.0:bindings:HTTP-Redirect" Version="2.0"
    xmlns:saml2p="urn:oasis:names:tc:SAML:2.0:protocol">