CDB3-327 dgf-english 500 server error when trying to send request without 'value' property

Summary: when I trying to send request without 'value' property, server responds with 500 error STR:

1. Go to /api/procedures endpoint.
2. Send POST request with body:

{
    "auctionPeriod": {
        "startDate": "2020-11-19T09:00:00+00:00"
    },
    "previousAuctionId": "UA-PS-1999-12-12-000000-0",
    "sellingMethod": "dgf-english",
    "sellingEntity": {
        "identifier": {
            "scheme": "UA-EDR",
            "legalName": {
                "uk_UA": "7777888",
                "en_US": "string"
            },
            "id": "88877779"
        },
        "address": {
            "addressID": {
                "scheme": "koatuu",
                "id": "0110136600"
            },
            "streetAddress": {
                "uk_UA": "string",
                "en_US": "string"
            },
            "locality": {
                "uk_UA": "string",
                "en_US": "string"
            },
            "region": {
                "uk_UA": "Автономна Республіка Кр",
                "en_US": "string"
            },
            "countryName": {
                "uk_UA": "gg"
            }
        },
        "contactPoint": {
            "email": "Tadmin@example.com",
            "telephone": "+380123456789",
            "name": {
                "uk_UA": "string",
                "en_US": "string"
            },
            "url": "http://string.com"
        },
        "representativeInfo": "Довіреність № 123 від 22.02.2012, дійсна до 30.03.2012/Наказ № 142 від 14.12.2019/Статут ТОВ Кульбаба від 24.07.2002"
    },
    "lotId": "string",
    "title": {
        "uk_UA": "string",
        "en_US": "string"
    },
    "description": {
        "uk_UA": "string",
        "en_US": "string"
    },
    "decision": {
        "decisionId": "string",
        "decisionDate": "2020-11-04T17:28:58.265Z"
    },
    "bankAccount": [
        {
            "bankName": {
                "uk_UA": "string",
                "en_US": "string"
            },
            "description": {
                "uk_UA": "string",
                "en_US": "string"
            },
            "accountIdentifications": [
                {
                    "scheme": "UA-EDR",
                    "id": "12345678"
                }
            ]
        }
    ],
    "x_documentRequirements": {
        "uk_UA": "string",
        "en_US": "string"
    },
    "x_additionalInformation": {
        "uk_UA": "string",
        "en_US": "string"
    },
    "discount": {
        "previousAuctionValue": {
            "currency": "UAH",
            "amount": 11,
            "valueAddedTaxIncluded": true
        },
        "discountPercent": 10.5,
        "discount": true
    },
    "guarantee": {
        "currency": "UAH",
        "amount":  2147483647466.99,
        "valueAddedTaxIncluded": true
    },
    "minimalStep": {
        "currency": "UAH",
        "amount": 1,
        "valueAddedTaxIncluded": true
    },
    "minNumberOfQualifiedBids": 0,
    "tenderAttempts": 2147483364474,
    "virtualDataRoom": "http://virtial-data-room.com/id_of_room",
    "eligibilityCriteria": "eligibilityCriteria",
    "accessDetails": {
        "uk_UA": "ssss"
    },
    "items": [
        {
            "description": {
                "uk_UA": "string",
                "en_US": "string"
            },
            "classification": {
                "scheme": "CAV",
                "id": "04000000-8"
            },
            "unit": {
                "code": "H87"
            },
            "quantity": 5,
            "address": {
                "addressID": {
                    "scheme": "koatuu",
                    "id": "0110136600"
                },
                "streetAddress": {
                    "uk_UA": "string",
                    "en_US": "string"
                },
                "locality": {
                    "uk_UA": "string",
                    "en_US": "string"
                },
                "region": {
                    "uk_UA": "Хмельницька область",
                    "en_US": "string"
                },
                "postalCode": "string",
                "countryName": {
                    "uk_UA": "Україна"
                }
            },
            "additionalClassifications": [
                {
                    "scheme": "CPVS",
                    "id": "QB49-3"
                }
            ],
            "location": {
                "latitude": "string",
                "longitude": "string",
                "elevation": "string"
            },
            "itemProps": {
                "totalBuildingArea": 12.5,
                "totalObjectArea": 2222.3,
                "constructionYear": 2020
            }
        }
    ]
}

X-Request-ID: 136a60b9-a398-4366-810f-a6c7804e9811

Actual result: 500 error

Expected result: should be like 422 resp_code with error text - ""value": "This field is required""