src/Validation/Spec/AbstractValidator.php
protected function dataHas($key): bool
    {
        if (!isset($this->document->data)) {
            return false;
        }

        return property_exists($this->document->data, $key);
    }
protected function dataHas($key): bool
    {
        if (!isset($this->document->data)) {
            return false;
        }

        return property_exists($this->document->data, $key);
    }
Does the key exist in document data object?

@param $key
@return bool