SectionData.php

<?php

namespace Drupal\layout_builder\Plugin\DataType;

use Drupal\Core\TypedData\TypedData;
use Drupal\layout_builder\Section;

/**
 * Provides a data type wrapping \Drupal\layout_builder\Section.
 *
 * @DataType(
 *   id = "layout_section",
 *   label = @Translation("Layout Section"),
 *   description = @Translation("A layout section"),
 * )
 *
 * @internal
 *   Plugin classes are internal.
 */
class SectionData extends TypedData {
    
    /**
     * The section object.
     *
     * @var \Drupal\layout_builder\Section
     */
    protected $value;
    
    /**
     * {@inheritdoc}
     */
    public function setValue($value, $notify = TRUE) {
        if ($value && !$value instanceof Section) {
            throw new \InvalidArgumentException(sprintf('Value assigned to "%s" is not a valid section', $this->getName()));
        }
        parent::setValue($value, $notify);
    }

}