Use bootstrap components

Hi,
I’m trying to apply this guide https://www.yiiframework.com/doc/guide/2.0/en/structure-extensions#bootstrapping-classes to an extension in order to load internationalization files of my extension during bootstrap. The problem is that the bootstrap method is never called.

If I add the created class to the bootstrap configuration property of my application the bootstrap method is correctly called.

Here my implementation:

From 2cb21d9fca6214df7cd6905078b142d6e902901b Mon Sep 17 00:00:00 2001
From: Liviu Calin <liviu.calin@yetopen.it>
Date: Mon, 29 Nov 2021 12:10:53 +0100
Subject: [PATCH] Bootstrap test

---
 Bootstrap.php                          | 23 +++++++++++++++++++++++
 composer.json                          |  3 +++
 dictionaries/UnitMeasureDictionary.php |  4 ++++
 messages/it/yohelpers.php              |  1 +
 4 files changed, 31 insertions(+)
 create mode 100644 Bootstrap.php

diff --git a/Bootstrap.php b/Bootstrap.php
new file mode 100644
index 0000000..96f620d
--- /dev/null
+++ b/Bootstrap.php
@@ -0,0 +1,23 @@
+<?php
+
+namespace yetopen\helpers;
+
+use yii\base\BootstrapInterface;
+
+class Bootstrap implements BootstrapInterface
+{
+    public function bootstrap($app)
+    {
+        \Yii::setAlias('@yohelpers', '@vendor/yetopen/yii2-helpers');
+        if (empty(\Yii::$app->i18n->translations['yohelpers'])) {
+            \Yii::$app->i18n->translations['yohelpers'] = [
+                'class' => 'yii\i18n\PhpMessageSource',
+                'basePath' => '@yohelpers/messages',
+                'fileMap' => [
+                    'yohelpers' => 'yohelpers.php',
+                ],
+            ];
+        }
+    }
+
+}
\ No newline at end of file
diff --git a/composer.json b/composer.json
index 3567b53..6d59bfa 100644
--- a/composer.json
+++ b/composer.json
@@ -12,5 +12,8 @@
         "psr-4": {
             "yetopen\\helpers\\": ""
         }
+    },
+    "extra": {
+        "bootstrap": "yetopen\\helpers\\Bootstrap"
     }
 }
-- 
GitLab

I’ve done composer update of the extension in the main application in order to get the modifications loaded through composer itself.

Am I missing something in order to get bootstrapping code being executed without the use of the configuration property?