Allow SAML with Office365 multidomains
The microsoft "cloud" login uses SAML 2 (POST) to delegate authentication to an SAML 2 IDP.
Office 365 uses this portal but to manage several domains, Office365 requires several SAML IDP. This is explained here: https://www.portalguard.com/blog/2016/08/25/office-365-federation-multiple-domains/
We must have a specific code to allows to change the Issuer value in SAML response, to support Office365 multidomains.