Localities endpoint sometimes returns district = null, contradicting Swagger (DE, states 01/02)

[jens-muenker]

The endpoint /de/FederalStates/{key}/Localities occasionally returns localities without district, although the Swagger marks district as required. The generated Kotlin client therefore fails with MissingKotlinParameterException.

Affected examples (DE):

• State 01 (Schleswig-Holstein), page 1: localities contain district

curl -X 'GET' \
  'https://openplzapi.org/de/FederalStates/02/Localities?page=1&pageSize=50' \
  -H 'accept: application/json'

• State 02 (Hamburg), page 1: localities does not contain district

curl -X 'GET' \
  'https://openplzapi.org/de/FederalStates/02/Localities?page=1&pageSize=50' \
  -H 'accept: application/json'

Swagger excerpt:
OpenPlzApi.DE.LocalityResponse lists district in required:

"OpenPlzApi.DE.LocalityResponse": {
        "required": [
          "district",
          "federalState",
          "municipality",
          "name",
          "postalCode"
        ],
        "type": "object",
        "properties": {
          "district": {
            "$ref": "#/components/schemas/OpenPlzApi.DE.DistrictSummary"
          },
          "federalState": {
            "$ref": "#/components/schemas/OpenPlzApi.DE.FederalStateSummary"
          },
          "municipality": {
            "$ref": "#/components/schemas/OpenPlzApi.DE.MunicipalitySummary"
          },
          "name": {
            "minLength": 1,
            "type": "string",
            "description": "Name (Ortsname)",
            "readOnly": true,
            "example": "Bendorf"
          },
          "postalCode": {
            "minLength": 1,
            "type": "string",
            "description": "Postal code (Postleitzahl)",
            "readOnly": true,
            "example": "56170"
          }
        },
        "additionalProperties": false,
        "description": "Representation of a German locality (Ort oder Stadt)",
        "readOnly": true
      }

Expected behavior:

• Either district is always present (never null/missing), or
• Swagger marks district as optional/nullable (not in required), so the generated client doesn’t crash.

Actual behavior:

• API responses sometimes contain district: null or omit the field.

Proposed fix:

• Either always include district in responses, or
• Mark district as optional/nullable in Swagger to match real responses.

[fstueber]

True, will fix by making it optional

[fstueber]

Fixed. Please check.