Source

File: wp-includes/class-wp-customize-manager.php

protected function get_lock_user_data( $user_id ) {
		if ( ! $user_id ) {
			return null;
		}
		$lock_user = get_userdata( $user_id );
		if ( ! $lock_user ) {
			return null;
		}
		return array(
			'id'     => $lock_user->ID,
			'name'   => $lock_user->display_name,
			'avatar' => get_avatar_url( $lock_user->ID, array( 'size' => 128 ) ),
		);
	}