NIFI-8025 - Refactored AccessResource SAML and OIDC endpoints into separate classes

[thenatog]

NIFI-8025 - Moved SAML to separate class and tested to be working.

NIFI-8025 - Added license to new files.

NIFI-8025 - Fixed a SAML logout consumer path.

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[exceptionfactory]

Thanks for refactoring the SAML and OIDC resources @thenatog, this should make it easier to maintain these features down the road. There may be some additional opportunities for improvement, and I realize most of this is just reorganizing things. There may be an opportunity to reduce some code duplication when checking for request security and method enabled status, but otherwise this seems straightforward.

[thenatog]

Updated PR to address latest feedback.

[exceptionfactory]

This line will close the httpClient, but now that it is a class member variable, it should not be closed in this method. Creating a new method annotated with @PreDestroy is one option for closing the HttpClient instance prior to application shutdown.

[thenatog]

Tried to commit this change but somehow 'Merge branch 'main' into NIFI-8025-rebased' happened. Will fix.

[exceptionfactory]

Thanks for working through the changes @thenatog! Verified SAML and OIDC with Keycloak, looks good! +1 Merging.