ExampleValueObject.php

<?php

class ExampleValueObject
{
    private string $value;

    /**
     * ExampleValueObject constructor.
     *
     * @param string $exampleValue some example value
     *
     */
    public function __construct(string $exampleValue)
    {
        if (empty($exampleValue)) {
            throw new InvalidArgumentException('value is empty');
        }

        $this->value = $exampleValue;
    }

    /**
     * @return string
     */
    public function __toString() : string
    {
        return $this->value;
    }

}