Classes/Console/Composer/InstallerScripts.php
public static function register(Event $event, ScriptDispatcher $scriptDispatcher)
    {
        $scriptDispatcher->addInstallerScript(new PopulateCommandConfiguration(), 70);
        if (!class_exists(\TYPO3\CMS\Core\Composer\InstallerScripts::class)
            && !class_exists(\Helhum\Typo3ComposerSetup\Composer\InstallerScripts::class)
            && $event->getComposer()->getRepositoryManager()->getLocalRepository()->findPackage('typo3/cms', new EmptyConstraint()) !== null
        ) {
            // @deprecated can be removed once TYPO3 8 support is removed
            $scriptDispatcher->addInstallerScript(new WebDirectory());
            $scriptDispatcher->addInstallerScript(new AutoloadConnector());
        }
    }
public static function register(Event $event, ScriptDispatcher $scriptDispatcher)
    {
        $scriptDispatcher->addInstallerScript(new PopulateCommandConfiguration(), 70);
        if (!class_exists(\TYPO3\CMS\Core\Composer\InstallerScripts::class)
            && !class_exists(\Helhum\Typo3ComposerSetup\Composer\InstallerScripts::class)
            && $event->getComposer()->getRepositoryManager()->getLocalRepository()->findPackage('typo3/cms', new EmptyConstraint()) !== null
        ) {
            // @deprecated can be removed once TYPO3 8 support is removed
            $scriptDispatcher->addInstallerScript(new WebDirectory());
            $scriptDispatcher->addInstallerScript(new AutoloadConnector());
        }
    }
Allows to register one or more script objects that implement this interface
This will be called in the Plugin right before the scripts are executed.

@param Event $event
@param ScriptDispatcher $scriptDispatcher
@return void