src/commands/ExtensionController.php
public function actionUpdateConfig()
    {
        $result = (int) (ExtensionFileWriter::updateConfig() !== true);

        if ($result === 0) {
            $this->stdout('Update OK' . PHP_EOL, Console::FG_GREEN);
        } else {
            $this->stderr('Error updating extensions storage: ', Console::FG_RED);
            $this->stderr(ExtensionsManager::module()->extensionsStorage . PHP_EOL);
        }

        return $result;
    }
public function actionUpdateConfig()
    {
        $result = (int) (ExtensionFileWriter::updateConfig() !== true);

        if ($result === 0) {
            $this->stdout('Update OK' . PHP_EOL, Console::FG_GREEN);
        } else {
            $this->stderr('Error updating extensions storage: ', Console::FG_RED);
            $this->stderr(ExtensionsManager::module()->extensionsStorage . PHP_EOL);
        }

        return $result;
    }
Updates config.
Calculates differences between @vengor/composer/installed.json and ExtensionsManager::$extensionsStorage
and writes new ExtensionsManager::$extensionsStorage