config-write causes syntax error with "retry-on-startup" database parameter

Problem: triggering a config-write API call encloses the boolean value of "retry-on-startup" within " which is a syntax error. A subsequent restart of Kea fails. I only tested hosts-database and lease-database but it could also apply to configuration backend.

Tested: 2.6.1

1. To reproduce,

start with a very simple configuration

{
  "Dhcp4": {
    "control-socket": {
      "socket-name": "/tmp/kea4-ctrl-socket",
      "socket-type": "unix"
    },
    "hooks-libraries": [
      {
        "library": "/usr/lib/x86_64-linux-gnu/kea/hooks/libdhcp_subnet_cmds.so"
      }
    ],
    "hosts-databases": [
      {
        "connect-timeout": 1,
        "host": "127.0.0.1",
        "max-reconnect-tries": 1800,
        "name": "kea",
        "on-fail": "stop-retry-exit",
        "password": "kea",
        "reconnect-wait-time": 1000,
        "retry-on-startup": true,
        "type": "postgresql",
        "user": "kea"
      }
    ],
    "lease-database": {
      "connect-timeout": 1,
      "host": "127.0.0.1",
      "max-reconnect-tries": 1800,
      "name": "kea",
      "on-fail": "stop-retry-exit",
      "password": "kea",
      "reconnect-wait-time": 1000,
      "retry-on-startup": false,
      "type": "postgresql",
      "user": "kea"
    },
  }
}

2. Run the server: sudo /usr/sbin/kea-dhcp4 -c /etc/kea/kea-dhcp4.conf
3. Trigger a config-write with the API: sudo echo '{"command": "config-write"}' | sudo socat UNIX:/tmp/kea4-ctrl-socket -,ignoreeof| jq .
4. Restart the server ctrl+c and

it fails to start

$ sudo /usr/sbin/kea-dhcp4 -c /etc/kea/kea-dhcp4.conf
2024-09-13 18:14:46.627 INFO  [kea-dhcp4.dhcp4/7970.140053932713024] DHCP4_STARTING Kea DHCPv4 server version 2.6.1 (stable) starting
2024-09-13 18:14:46.629 ERROR [kea-dhcp4.dhcp4/7970.140053932713024] DHCP4_CONFIG_LOAD_FAIL configuration error using file: /etc/kea/kea-dhcp4.conf, reason: /etc/kea/kea-dhcp4.conf:63.29-34: syntax error, unexpected constant string, expecting boolean
2024-09-13 18:14:46.629 ERROR [kea-dhcp4.dhcp4/7970.140053932713024] DHCP4_INIT_FAIL failed to initialize Kea server: configuration error using file '/etc/kea/kea-dhcp4.conf': /etc/kea/kea-dhcp4.conf:63.29-34: syntax error, unexpected constant string, expecting boolean

5. Check configuration file and find that the "retry-on-startup": true, and "retry-on-startup": false, are now "retry-on-startup": "true", and "retry-on-startup": "false", respectively.
6. Remove the extra " surrounding the boolean values of "retry-on-startup" throughout the configuration and it will again start.

Configuration file post config-write: kea-dhcp4.conf