wp-includes/Requests/src/Utility/InputValidator.php:58Verify whether a received input parameter is "stringable".
$inputmixedbool public static function is_stringable_object($input) { return is_object($input) && method_exists($input, '__toString'); }Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/Requests/src/Utility/InputValidator.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.