wp-includes/embed.php:763Ensures that the specified format is either 'json' or 'xml'.
$formatstringstringfunction wp_oembed_ensure_format( $format ) { if ( ! in_array( $format, array( 'json', 'xml' ), true ) ) { return 'json'; } return $format;}Introduced in 4.4.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/embed.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.