protected function getDoctrineColumnOptions(ColumnDefinition $columnMetadata)
    {
        $options = $columnMetadata['options'];

        // alias for nullable option
        if (! empty($columnMetadata['nullable'])) {
            $options['notnull'] = ! $columnMetadata['nullable'];
        }

        // alias for default option
        if (! empty($columnMetadata['default'])) {
            $options['default'] = $columnMetadata['default'];
        }

        // alias for unsigned option
        if (! empty($columnMetadata['options']['unsigned'])) {
            $options['unsigned'] = $columnMetadata['options']['unsigned'];
        }

        // alias for autoincrement option
        if (! empty($columnMetadata['options']['autoIncrement'])) {
            $options['autoincrement'] = $columnMetadata['options']['autoIncrement'];
        }

        // alias for fixed option
        if (! empty($columnMetadata['options']['fixed'])) {
            $options['fixed'] = $columnMetadata['options']['fixed'];
        }

        return $options;
    }