src/Validation/CallbackValidator.php
public function isValid($value)
    {
        if (call_user_func($this->callable, $value)) {
            $this->errorMessage = '';
            return true;
        }
        $this->errorMessage = str_replace('%VALUE%', print_r($value, true), $this->errorMessageTemplate);
        return false;
    }
public function isValid($value)
    {
        if (call_user_func($this->callable, $value)) {
            $this->errorMessage = '';
            return true;
        }
        $this->errorMessage = str_replace('%VALUE%', print_r($value, true), $this->errorMessageTemplate);
        return false;
    }
{@inheritdoc}