wp-includes/class-wp-customize-panel.php:309Render the panel container, and then its contents (via this->render_content()) in a subclass.
protected function render() {}Introduced in 4.0.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/class-wp-customize-panel.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.