Why `if (false)`? - it's for composer authoritative classmap

gistfile1.txt

https://github.com/symfony/symfony/blob/master/src/Symfony/Bridge/PhpUnit/TextUI/TestRunner.php

namespace Symfony\Bridge\PhpUnit\TextUI;

if (class_exists('PHPUnit_Runner_Version') && version_compare(\PHPUnit_Runner_Version::id(), '6.0.0', '<')) {
    class_alias('Symfony\Bridge\PhpUnit\Legacy\TestRunnerForV5', 'Symfony\Bridge\PhpUnit\TextUI\TestRunner');
} elseif (version_compare(\PHPUnit\Runner\Version::id(), '7.0.0', '<')) {
    class_alias('Symfony\Bridge\PhpUnit\Legacy\TestRunnerForV6', 'Symfony\Bridge\PhpUnit\TextUI\TestRunner');
} else {
    class_alias('Symfony\Bridge\PhpUnit\Legacy\TestRunnerForV7', 'Symfony\Bridge\PhpUnit\TextUI\TestRunner');
}
if (false) {
    class TestRunner
    {
    }
}