VO5.php

<?php
declare(strict_types=1);

final class CustomerName
{
    private $firstName;

    private $lastName;

    public function __construct(string $firstName, string $lastName)
    {
        Assert::stringNotEmpty($firstName);
        Assert::stringNotEmpty($lastName);
        Assert::alpha($firstName);
        Assert::alpha($lastName);

        $this->firstName = $firstName;
        $this->lastName = $lastName;
    }

    public static function fromFullName(string $fullname): self
    {
        $pieces = explode(' ', $fullname);

        return new CustomerName($pieces[0], $pieces[1]);
    }
}