src/Plugin.php
public function activate(Composer $composer, IOInterface $io)
    {
        $packageInstallerTrigger = new PackageInstallerTrigger($io, $composer);
        $composer->getInstallationManager()->addInstaller($packageInstallerTrigger);

        $this->composer = $composer;
        $this->io = $io;
        $this->packageInstallerTrigger = $packageInstallerTrigger;

        $extraSettings = $this->composer->getPackage()->getExtra();
        if (isset($extraSettings[AbstractPackageInstaller::EXTRA_PARAMETER_KEY_ROOT])) {
            $this->packageInstallerTrigger->setSettings($extraSettings[AbstractPackageInstaller::EXTRA_PARAMETER_KEY_ROOT]);
        }
    }
public function activate(Composer $composer, IOInterface $io)
    {
        $packageInstallerTrigger = new PackageInstallerTrigger($io, $composer);
        $composer->getInstallationManager()->addInstaller($packageInstallerTrigger);

        $this->composer = $composer;
        $this->io = $io;
        $this->packageInstallerTrigger = $packageInstallerTrigger;

        $extraSettings = $this->composer->getPackage()->getExtra();
        if (isset($extraSettings[AbstractPackageInstaller::EXTRA_PARAMETER_KEY_ROOT])) {
            $this->packageInstallerTrigger->setSettings($extraSettings[AbstractPackageInstaller::EXTRA_PARAMETER_KEY_ROOT]);
        }
    }
Register shop packages installer.

@param Composer    $composer
@param IOInterface $io