Symfony's vendors causing autoloader psr-4 warnings when running composer - symfony

Question

For years, I have been getting these warning whenever I run composer install:
Generating optimized autoload files (authoritative) Class
Sensio\Bundle\FrameworkExtraBundle\Tests\DependencyInjection\AddParamConverterPassTest
located in
./vendor/sensio/framework-extra-bundle/Tests/DependencyInjection/Compiler/AddParamConverterPassTest.php
does not comply with psr-4 autoloading standard. Skipping. Class
Sensio\Bundle\FrameworkExtraBundle\Tests\DependencyInjection\AddExpressionLanguageProvidersPassTest
located in
./vendor/sensio/framework-extra-bundle/Tests/DependencyInjection/Compiler/AddExpressionLanguageProvidersPassTest.php
does not comply with psr-4 autoloading standard. Skipping. Class
Sensio\Bundle\FrameworkExtraBundle\Tests\Request\ParamConverter\ArgumentNameConverterTest
located in
./vendor/sensio/framework-extra-bundle/Tests/Request/ArgumentNameConverterTest.php
does not comply with psr-4 autoloading standard. Skipping. Class
Doctrine\Bundle\MigrationsBundle\Tests\DependencyInjection\DoctrineCommandTest
located in
./vendor/doctrine/doctrine-migrations-bundle/Tests/Command/DoctrineCommandTest.php
does not comply with psr-4 autoloading standard. Skipping.
How could I get rid of these vendor caused warnings?
My composer.json:
{
"name": "...",
"description": "...",
"license": "MIT",
"type": "project",
"autoload": {
"psr-4": {
"AppBundle\\": "src/AppBundle"
},
"classmap": [ "app/AppKernel.php", "app/AppCache.php" ]
},
"autoload-dev": {
"psr-4": {
"Tests\\": "tests/",
"Features\\": "features/"
},
"files": [ "vendor/symfony/symfony/src/Symfony/Component/VarDumper/Resources/functions/dump.php" ]
},
"require": {
"php": "^7.2",
"aws/aws-sdk-php": "3.178.*",
"bentools/webpush-bundle": "0.6.*",
"doctrine/doctrine-bundle": "1.12.*",
"doctrine/doctrine-migrations-bundle": "1.3.*",
"doctrine/orm": "2.6.*",
"endroid/qr-code-bundle": "3.4.*",
"friendsofsymfony/jsrouting-bundle": "2.4.*",
"google/apiclient": "2.12.*",
"google/recaptcha": "1.2.*",
"incenteev/composer-parameter-handler": "2.1.*",
"knplabs/knp-time-bundle": "1.15.*",
"sensio/framework-extra-bundle": "5.2.*",
"sonata-project/admin-bundle": "3.76.0",
"sonata-project/core-bundle": "3.20.0",
"sonata-project/doctrine-orm-admin-bundle": "3.24.*",
"stripe/stripe-php": "7.102.*",
"symfony/asset": "4.4.*",
"symfony/monolog-bundle": "3.4.*",
"symfony/orm-pack": "2.2.*",
"symfony/polyfill-apcu": "1.12.*",
"symfony/swiftmailer-bundle": "3.1.*",
"symfony/symfony": "4.4.*",
"symfony/twig-bundle": "4.4.*",
"symfony/webpack-encore-bundle": "1.14.*",
"twig/cssinliner-extra": "3.3.*",
"twig/twig": "2.14.*",
"ua-parser/uap-php": "3.9.*"
},
"require-dev": {
"behat/behat": "3.7.*",
"behat/mink": "1.8.*",
"behat/mink-browserkit-driver": "1.3.*",
"behat/mink-extension": "2.3.*",
"behat/mink-goutte-driver": "1.2.1",
"behat/mink-selenium2-driver": "1.2.0",
"behat/symfony2-extension": "2.1.*",
"phpunit/phpunit": "8.5.*",
"symfony/browser-kit": "4.4.*",
"symfony/phpunit-bridge": "6.0.*",
"symfony/test-pack": "1.0.*"
},
"scripts": {
"symfony-scripts": [
"Incenteev\\ParameterHandler\\ScriptHandler::buildParameters"
],
"post-install-cmd": [
"#symfony-scripts"
],
"post-update-cmd": [
"#symfony-scripts"
]
},
"config": {
"platform": {
"php": "7.2.32"
},
"sort-packages": true
},
"extra": {
"incenteev-parameters": {
"file": "app/config/parameters.yml"
},
"branch-alias": {
"dev-master": "3.4-dev"
}
}
}

Answer 1

If the code is not under your control (vendor code), then you cannot really fix the issue. Either:
you upgrade your dependencies (which could be difficult and problematic, depending on your project, but ultimately the best way forward)
you downgrade Composer to a version that does not raise that warning. That wouldn't be a recommended course of action. You'd lose in performance at the very least, and miss out on bugfixes of later versions.
you ignore the warnings, since warnings are not errors, doubly so on warnings that are shown during installation and not during application rutime.