commands lease4-get-by-* returning empty parameters in not consistent way.

Example show lease of client that send hostname and client-id; both are returned in lease4-get-by-* commands

{'arguments': {'hostname': 'four.hostname.com.'}, 'command': 'lease4-get-by-hostname'}

{
  "arguments": {
    "leases": [
      {
        "client-id": "00:01:02:03:04:05:06",
        "cltt": 1597923930,
        "fqdn-fwd": true,
        "fqdn-rev": true,
        "hostname": "four.hostname.com.",
        "hw-address": "08:08:08:08:08:08",
        "ip-address": "192.168.50.5",
        "state": 0,
        "subnet-id": 1,
        "valid-lft": 4000
      }
    ]
  },
  "result": 0,
  "text": "1 IPv4 lease(s) found."
}

but when client will not send hostname nor client-id response is this:

{
  "arguments": {
    "leases": [
      {
        "cltt": 1597924174,
        "fqdn-fwd": false,
        "fqdn-rev": false,
        "hostname": "",
        "hw-address": "10:10:10:10:10:10",
        "ip-address": "192.168.51.10",
        "state": 0,
        "subnet-id": 2,
        "valid-lft": 4000
      }
    ]
  },
  "result": 0,
  "text": "1 IPv4 lease(s) found."
}

parameter hostname is included but it's empty, and client-id is missing. It should also be included as an empty parameter.