Steps to reproduce:

• Go to /zabbix.php?action=discovery.list
• Open "Local network" discovery rule edit form
• Enable the rule, update IP range and discovery check => replace Zabbix agent to HTTP with default port or use API request e.g.

{
    "jsonrpc": "2.0",
    "method": "drule.update",
    "iprange": {valid_ip_range},
    "params": {
        "druleid": "2",
        "dchecks": [
            {
                "dcheckid": "2",
                "type": "4",
                "ports": "80"
            }
        ]
    },
    "id": 1
}

• save the configuration
• run zabbix server
• Check dchecks table _key parameter
• Check Monitoring => Discovery page

Result: drule.update doesn't overrides _key value.
Network discovery reult =>

Note: The same issue appears with snmp fields.

Expected: dcheck type unrelated parameters should be overridden with empty values.