How to integrate this with legacy java webapp web.xml filter for saml2 authentication

[sudheer4java]

Is your feature request related to a problem? Please describe.
I have lot of legacy apps running with cas and trying update to saml 2.0 . created a micro service running with this code and integrated this with ping idp and authentication works from this saml sp to idp. but when i am trying to integrate with legacy java webapps i am unable to do that. Could you please help me to integrate with legacy web.xml with filter ? any link or doc please ?

Describe the solution you'd like
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Describe alternatives you've considered
i tried to create a local store to for saml auth tokens and but unable to get via filter code as this service provider returning sping authentication.

Additional context
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