Create a metadata value.

curl -X POST "<API_URL>/api/v1/metadata-values" \
  -H "Authorization: Bearer <API_KEY>" \
  -H "Content-Type: application/json" \
  -d '{
    "metadataValue": {
      "key": {
        "name": "string",
        "type": "METADATA_KEY_TYPE_UNSPECIFIED",
        "archivedDate": "2019-08-24T14:15:22Z"
      },
      "stringValue": "string",
      "numberValue": 0.1,
      "booleanValue": true,
      "archivedDate": "2019-08-24T14:15:22Z"
    }
  }'