Defines md:IDPSSODescriptorType as defined by
https://www.oasis-open.org/committees/download.php/35391/sstc-saml-metadata-errata-2.0-wd-04-diff.pdf
Page 19, Line 792
Implementation saml:Issuer as defined by
https://www.oasis-open.org/committees/download.php/35711/sstc-saml-core-errata-2.0-wd-06-diff.pdf
Page 15, Line 564
Issuer() - Constructor for class org.springframework.security.saml.saml2.authentication.Issuer