Updates the comment cache of given comments.

Will add the comments in $comments to the cache. If comment ID already exists
in the comment cache then it will not be updated. The comment is added to the
cache using the comment group with the key using the ID of the comments.

function update_comment_cache( $comments, $update_meta_cache = true ) {
	$data = array();
	foreach ( (array) $comments as $comment ) {
		$data[ $comment->comment_ID ] = $comment;
	}
	wp_cache_add_multiple( $data, 'comment' );

	if ( $update_meta_cache ) {
		// Avoid `wp_list_pluck()` in case `$comments` is passed by reference.
		$comment_ids = array();
		foreach ( $comments as $comment ) {
			$comment_ids[] = $comment->comment_ID;
		}
		update_meta_cache( 'comment', $comment_ids );
	}
}