minor #16733 [Security] Add InteractiveAuthenticatorInterface reference (Florian-B)

This PR was merged into the 5.4 branch.

Discussion
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[Security] Add InteractiveAuthenticatorInterface reference

Add a tip to explain how to make a custom authenticator dispatch an InteractiveLoginEvent

Commits
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3ae47aa Add InteractiveAuthenticatorInterface reference

Author: javiereguiluz

security/custom_authenticator.rst

@@ -176,6 +176,13 @@ can define what happens in these cases:
     above. Use :class:`Symfony\\Component\\Security\\Core\\Exception\\CustomUserMessageAuthenticationException`
     if you want to set custom error messages.
 
+.. tip::
+
+    If your login method is interactive, which means that the user actively logged into your application, you may want your authenticator to implement the 
+    :class:`Symfony\\Component\\Security\\Http\\Authenticator\\InteractiveAuthenticatorInterface`
+    so that it dispatches an 
+    :class:`Symfony\\Component\\Security\\Http\\Event\\InteractiveLoginEvent`
+
 .. _security-passport:
 
 Security Passports