| Property Name | Type | Description | Available Version |
|---|---|---|---|
| alternativeRepresentation | ConnectApi.Alternative | Alternative representation of the extension. | 40.0 |
| attachmentId | String | Attachment ID of the extension. | 41.0 |
| extensionId | String | ID of the extension. | 40.0 |
| payload | String | Payload associated with the extension. | 40.0 |
| payloadVersion | String | Payload version that identifies the structure of the payload associated with the extension. | 40.0 |