How to find where are defined tokens for Redirect?

Question

After enabling Token and Redirect modules, I've found at /admin/help/token that I can use Redirect tokens. For example:

However, I've got the problem finding the place where and how these tokens are defined (which file and hook or class).

Any ideas?

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I've tried to search inside all files in docroot, e.g.

$ grep -r "The URL of the redirect" .
(nothing)
$ grep -r "The URL of the" .
(returns everything apart of redirect, no matching placeholders found)
$ grep -r token modules/contrib/redirect/
modules/contrib/redirect/config/install/views.view.redirect.yml:          tokenize: false
modules/contrib/redirect/modules/redirect_404/config/install/views.view.redirect_404.yml:          tokenize: false
modules/contrib/redirect/modules/redirect_404/redirect_404.routing.yml:    _csrf_token: 'TRUE'
modules/contrib/redirect/src/EventSubscriber/RouteNormalizerRequestSubscriber.php:      // Strip off query parameters added by the route such as a CSRF token.
$ grep -r redirect modules/contrib/token/
modules/contrib/token/src/Controller/TokenCacheController.php:   * Clear caches and redirect back to the frontpage.
modules/contrib/token/src/Controller/TokenCacheController.php:    return $this->redirect('<front>');
$ find modules/contrib/redirect modules/contrib/token -name "*.tokens.inc"
modules/contrib/token/tests/modules/token_module_test/token_module_test.tokens.inc
modules/contrib/token/token.tokens.inc (Note: nothing here for redirect)

So basically I couldn't find the source which module is defining those. This can help me in order to find out, why some of them aren't working as expected.

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The main reason I ask this, because I would expect for redirect URL such as /foo/XXX, to return XXX when using [redirect:url:args:last], but these tokens aren't populated at all.

Answer 1

As Clive mentioned, since Redirect is an entity, those tokens are automatically generated by the Token module's token.tokens.inc.

I suggest you read Custom Tokens in Drupal 8 to understand how they are declared & work.