config-set problem with output_options in loggers

Affects versions: 2.4.0, 2.6.0 (I did not test other versions)

Sending config-set sending a configuration that has output_options in the "loggers" section causes the the entire output_options section to disappear from the "loggers" configuration.

Steps to reproduce:

1. Start with a simple configuration

The simple configuration

{
  "Dhcp4": {
    "control-socket": {
      "socket-name": "/tmp/socket-dhcp4",
      "socket-type": "unix"
    },
    "loggers": [
      {
        "name": "kea-dhcp4",
        "output_options": [
          {
            "output": "/var/log/kea/kea-dhcp4.log",
            "maxsize": 1073741824,
            "maxver": 5
          }
        ],
        "severity": "DEBUG",
        "debuglevel": 99
      }
    ]
  }
}

2. Send the same or a modified configuration with config-set (the loggers section unchanged). Note that logging to the file stops.

a slightly different configuration sent

{
  "command": "config-set",
  "arguments": {
    "Dhcp4": {
      "control-socket": {
        "socket-name": "/tmp/socket-dhcp4",
        "socket-type": "unix"
      },
      "loggers": [
        {
          "name": "kea-dhcp4",
          "output_options": [
            {
              "output": "/var/log/kea/kea-dhcp4.log",
              "maxsize": 1073741824,
              "maxver": 5
            }
          ],
          "severity": "DEBUG",
          "debuglevel": 99
        }
      ]
    }
  }
}

3. Now send a config-get and notice that the output_options section is gone:

result of config-get

{
  "arguments": {
    "Dhcp4": {
      "allocator": "iterative",
      "authoritative": false,
      "boot-file-name": "",
      "calculate-tee-times": true,
      "control-socket": {
        "socket-name": "/tmp/socket-dhcp4",
        "socket-type": "unix"
      },
      "ddns-conflict-resolution-mode": "check-with-dhcid",
      "ddns-generated-prefix": "myhost",
      "ddns-override-client-update": false,
      "ddns-override-no-update": false,
      "ddns-qualifying-suffix": "",
      "ddns-replace-client-name": "never",
      "ddns-send-updates": true,
      "ddns-update-on-renew": false,
      "decline-probation-period": 86400,
      "dhcp-ddns": {
        "enable-updates": false,
        "max-queue-size": 1024,
        "ncr-format": "JSON",
        "ncr-protocol": "UDP",
        "sender-ip": "0.0.0.0",
        "sender-port": 0,
        "server-ip": "127.0.0.1",
        "server-port": 53001
      },
      "dhcp-queue-control": {
        "capacity": 64,
        "enable-queue": false,
        "queue-type": "kea-ring4"
      },
      "dhcp4o6-port": 0,
      "early-global-reservations-lookup": false,
      "echo-client-id": true,
      "expired-leases-processing": {
        "flush-reclaimed-timer-wait-time": 25,
        "hold-reclaimed-time": 3600,
        "max-reclaim-leases": 100,
        "max-reclaim-time": 250,
        "reclaim-timer-wait-time": 10,
        "unwarned-reclaim-cycles": 5
      },
      "hooks-libraries": [],
      "host-reservation-identifiers": [
        "hw-address",
        "duid",
        "circuit-id",
        "client-id"
      ],
      "hostname-char-replacement": "",
      "hostname-char-set": "[^A-Za-z0-9.-]",
      "interfaces-config": {
        "interfaces": [],
        "re-detect": false
      },
      "ip-reservations-unique": true,
      "lease-database": {
        "type": "memfile"
      },
      "loggers": [
        {
          "debuglevel": 99,
          "name": "kea-dhcp4",
          "severity": "DEBUG"
        }
      ],
      "match-client-id": true,
      "multi-threading": {
        "enable-multi-threading": true,
        "packet-queue-size": 64,
        "thread-pool-size": 0
      },
      "next-server": "0.0.0.0",
      "option-data": [],
      "option-def": [],
      "parked-packet-limit": 256,
      "reservations-global": false,
      "reservations-in-subnet": true,
      "reservations-lookup-first": false,
      "reservations-out-of-pool": false,
      "sanity-checks": {
        "extended-info-checks": "fix",
        "lease-checks": "warn"
      },
      "server-hostname": "",
      "server-tag": "",
      "shared-networks": [],
      "stash-agent-options": false,
      "statistic-default-sample-age": 0,
      "statistic-default-sample-count": 20,
      "store-extended-info": false,
      "subnet4": [],
      "t1-percent": 0.5,
      "t2-percent": 0.875,
      "valid-lifetime": 7200
    },
    "hash": "E444209F41F22451DABB7B2EA5B0DBBF609B49392514FECDB2D5BB41A8929D4C"
  },
  "result": 0
}

Note that if step 2 above is repeated using output-options instead of output_options then the section does NOT disappear.

Further note that 2.4.0 accepts either output-options

RT23984