Unknown setting: mail_plugins

[Graf]

Hello!

At the start dovecot complains all occurrences |mail_plugins settings 
|in all configs.
For example 20-lmtp.conf contents:

|protocol lmtp {
    mail_plugins = $mail_plugins quota
}


# doveconf | grep '\(mail_plugin_dir\|mail_plugins\)'
doveconf: Fatal: Error in configuration file 
/etc/dovecot/conf.d/20-lmtp.conf line 2: Unknown setting: mail_plugins
||
|||
If I insert directly those strings in dovecot.conf and comment the 
!include conf.d/*.conf , I have no errors:

# doveconf | grep '\(mail_plugin_dir\|mail_plugins\)'
mail_plugin_dir = /usr/lib64/dovecot
mail_plugins =
   mail_plugins = " quota"

My settings:

|# dovecot --version
2.2.24 (a82c823)

# dovecot --build-options
Build options: ioloop=epoll notify=inotify ipv6 openssl io_block_size=8192
Mail storages: shared mdbox sdbox maildir mbox cydir imapc pop3c raw fail
SQL drivers: mysql sqlite
Passdb: checkpassword ldap passwd passwd-file shadow sql
Userdb: checkpassword ldap nss passwd prefetch passwd-file sql|

|# ls -l /usr/lib64/dovecot/ | grep quota
-rwxr-xr-x 1 root root     990 may 12 18:52 lib10_quota_plugin.la
-rwxr-xr-x 1 root root   78696 may 12 18:52 lib10_quota_plugin.so
-rwxr-xr-x 1 root root    1061 may 12 18:52 lib11_imap_quota_plugin.la
-rwxr-xr-x 1 root root   11584 may 12 18:52 lib11_imap_quota_plugin.so
-rwxr-xr-x 1 root root    1026 may 12 18:52 lib20_quota_clone_plugin.la
-rwxr-xr-x 1 root root    8992 may 12 18:52 lib20_quota_clone_plugin.so|

Thank you in advance.