remote-class6-get does not return max-preferred-lifetime, min-preferred-lifetime and preferred-lifetime on MySQL

When sending remote-class6-get, Kea does not return max-preferred-lifetime, min-preferred-lifetime and preferred-lifetime values set for this class when using MySQL Backend. If using PostgreSQL backend, values are returned.

Values were set using remote-class6-set

MySQL response:

[
  {
    "arguments": {
      "client-classes": [
        {
          "max-valid-lifetime": 1200,
          "metadata": {
            "server-tags": [
              "abc"
            ]
          },
          "min-valid-lifetime": 100,
          "name": "foo",
          "only-if-required": true,
          "option-data": [
            {
              "always-send": true,
              "code": 7,
              "csv-format": true,
              "data": "123",
              "name": "preference",
              "never-send": false,
              "space": "dhcp6"
            }
          ],
          "test": "member('UNKNOWN')",
          "valid-lifetime": 1000
        }
      ],
      "count": 1
    },
    "result": 0,
    "text": "DHCPv6 client class 'foo' found."
  }
]

PostgreSQL response:

[
  {
    "arguments": {
      "client-classes": [
        {
          "max-preferred-lifetime": 901,
          "max-valid-lifetime": 1200,
          "metadata": {
            "server-tags": [
              "abc"
            ]
          },
          "min-preferred-lifetime": 789,
          "min-valid-lifetime": 100,
          "name": "foo",
          "only-if-required": true,
          "option-data": [
            {
              "always-send": true,
              "code": 7,
              "csv-format": true,
              "data": "123",
              "name": "preference",
              "never-send": false,
              "space": "dhcp6"
            }
          ],
          "preferred-lifetime": 850,
          "test": "member('UNKNOWN')",
          "valid-lifetime": 1000
        }
      ],
      "count": 1
    },
    "result": 0,
    "text": "DHCPv6 client class 'foo' found."
  }
]