The left angle bracket at the beginning of the certificate path

[Илья]

dovecot 2.2.27 (c0f36b0) openSUSE Tumbleweed x86_64
https://forums.opensuse.org/showthread.php/521796-Dovecot-doveconf-Fatal-execvp(-usr-lib-dovecot-managesieve)-failed-Argument-list-too-long
Faced with an unpleasant situation, when ssl_client_ca_file options are
specified path to the left angle bracket, as in options ssl_key ssl_cert
ssl_ca path is so.
This doveconf shows no syntax error, and the arrow moves to managesieve
which there generally is not involved in any side.

dovecot: doveconf: Fatal: execvp(/usr/lib/dovecot/managesieve) failed:
Argument list too long
dovecot: config: Error: managesieve-login: dump-capability process returned
89

I consider this a bug, and that it should not be.

And explain why you need left angle brackets in the options ssl_key
ssl_cert ssl_ca?