DBSocket default is /tmp/mysql.sock, but default is NULL in source and it uses libmysqlclient library's default.
(1) remove default parameter
Zabbix doesn't use /tmp/mysql.sock. It's better to remove it
(2) update documentation and description in configuration file
It's better to explain it in description. Documentation also should be updated.
(3) DBport parameter
DBPort parameter also uses database client library default. MySQL Port is mentioned in the descripiotn and documentation now. It's better to update it same as DBSocket way above.