wp-includes/SimplePie/src/Item.php:368Get the media:thumbnail of the item
array|null public function get_thumbnail() { if (!isset($this->data['thumbnail'])) { if ($return = $this->get_item_tags(\SimplePie\SimplePie::NAMESPACE_MEDIARSS, 'thumbnail')) { $thumbnail = $return[0]['attribs']['']; if (empty($thumbnail['url'])) { $this->data['thumbnail'] = null; } else { $thumbnail['url'] = $this->sanitize($thumbnail['url'], \SimplePie\SimplePie::CONSTRUCT_IRI, $this->get_base($return[0])); $this->data['thumbnail'] = $thumbnail; } } else { $this->data['thumbnail'] = null; } } return $this->data['thumbnail']; }One change between 6.7.7 and 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
array|null to SimplePie\array{url:.verified against sourcesrc/wp-includes/SimplePie/src/Item.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.