WordPress function that uses filter "wp_head" to add meta robots noindex for password protected pages

ep_noindex_password_protected_pages.php

<?php

// if current page is password protected then kindly tell google (aka search engines) to not index the current page
function ep_noindex_password_protected_pages() {

	global $wp_the_query;

	if ( $wp_the_query->is_singular && post_password_required( $wp_the_query->get_queried_object ) ) {
		wp_no_robots();
	}

}
add_action("wp_head", "ep_noindex_password_protected_pages");