BaseFileConstraintValidator.php

<?php

declare (strict_types=1);
namespace Drupal\file\Plugin\Validation\Constraint;

use Drupal\file\FileInterface;
use Symfony\Component\Validator\ConstraintValidator;
use Symfony\Component\Validator\Exception\UnexpectedTypeException;

/**
 * Provides a base class for file constraint validators.
 */
abstract class BaseFileConstraintValidator extends ConstraintValidator {
    
    /**
     * Checks the value is of type FileInterface.
     *
     * @param mixed $value
     *   The value to check.
     *
     * @return \Drupal\file\FileInterface
     *   The file.
     *
     * @throw Symfony\Component\Validator\Exception\UnexpectedTypeException
     *   Thrown if the value is not a FileInterface.
     */
    protected function assertValueIsFile(mixed $value) : FileInterface {
        if (!$value instanceof FileInterface) {
            throw new UnexpectedTypeException($value, FileInterface::class);
        }
        return $value;
    }

}