Name Mapper Class from SAML 2.0 Service Provider is never called

We have an Web Application that uses WebLogic LDAP for authorization and authentication. Now SSO with Azure should be implemented. The username on Azure side is different to the LDAP user. The LDAP user should be passed as assertion parameter from Azure to WebLogic.

I configured SAML 2.0 ServiceProvider in WebLogic 12.2.1.4 on a local Windows machine as described in Oracle documentation with Virtual Users.

Now when I call my web application I'm redirected to the Azure login and can login there.

But then I found no way to access the logged in user or the attributes from SAML service provider.

I defined the "Name Mapper Class Name" from SAML2IdentitiyAsserter and also the "Identiy Provider Name Mapper Class Name".