src/Filter/Setting/SimpleLookup.php
protected function getLabel()
    {
        if (null === ($attribute = $this->getFilteredAttribute())) {
            return null;
        }
        if ($label = $this->get('label')) {
            return $label;
        }

        return $attribute->getName();
    }
protected function getLabel()
    {
        if (null === ($attribute = $this->getFilteredAttribute())) {
            return null;
        }
        if ($label = $this->get('label')) {
            return $label;
        }

        return $attribute->getName();
    }
Return the label to use.

@return string|null