Why Gnus is creating .nnmaildir directory in my maildir?

[Utkarsh Singh]

Hi,

I am trying to configure Gnus on my GNU/Linux system.  I will first
try to give background for my problem.

1. I am using mbsync/isync to fetch mail.
2. msmtp as `sendmail-program'.
3. '~/.local/share/mail/email-id' as maildir.
4. notmuch as mail indexer.

Overview of my maildir:
~/.local/share/mail/utkarsh190601@gmail.com $ ls
INBOX  [Gmail].Drafts     [Gmail].Sent       [Gmail].Spam     [Gmail].Trash
Sent   [Gmail].Important  [Gmail].Sent Mail  [Gmail].Starred

*Problem: Gnus is creating .nnmaildir directory in my maildir.*

Due to this whenever I try to run 'notmuch new' (command to update
indexer database) it gives several lines long warning:
ignoring non-mail file .nnmaildir/cur/..'

I think there is something wrong with my setup because no other email
client creates extra file when reading maildir (neomutt, notmuch-mua).

Snippets from my config:
;; gnus leave my ~
(setq gnus-home-directory (concat user-emacs-directory "gnus/"))
(setq gnus-directory (concat user-emacs-directory "/gnus/news/"))
(setq gnus-dribble-directory gnus-home-directory)

(setq gnus-select-method '(nnnil ""))
(setq gnus-secondary-select-methods
      '((nntp "news.gwene.org")
        (nnmaildir "utkarsh190601@gmail.com"
                    (directory "~/.local/share/mail/utkarsh190601@gmail.com"))))

--
Utkarsh Singh
http://utkarshsingh.xyz