curl --request PUT \
  --url https://{cluster}.voucherify.io/management/v1/projects/{projectId}/custom-event-schemas/{customEventSchemaId} \
  --header 'Content-Type: application/json' \
  --header 'X-Management-Id: <api-key>' \
  --header 'X-Management-Token: <api-key>' \
  --data '{
  "schema": {
    "properties": {}
  }
}'

{
  "id": "ms_u3bIQLbdU0fi3rhqpTLiF26T",
  "related_object": "reward",
  "properties": {
    "region": {
      "type": "string",
      "array": true,
      "optional": false,
      "object_type": null,
      "eq": [
        "EMEA",
        "APAC",
        "LATAM",
        "NA",
        "EU"
      ]
    }
  },
  "allow_defined_only": false,
  "created_at": "2024-04-29T12:03:55.991Z",
  "updated_at": "2024-04-29T12:06:20.866Z",
  "object": "metadata_schema"
}