default @NonNull IndexCommandResult<C> queryRootIndex(final @NonNull C sender) {
        return (IndexCommandResult<C>) this.query(HelpQuery.of(sender, ""));
    }
Queries for the root result. This is the result from invoking {@link #query(HelpQuery)} with an empty string.

@param sender the sender
@return the result
cloud-core/src/main/java/org/incendo/cloud/help/HelpHandler.java