| Name | Type | Description | Notes |
|---|---|---|---|
| type | String | The type of action. | [default to 'postback'] |
| text | String | The button text. | |
| payload | String | The payload of a postback or reply button. | |
| metadata | Object | Flat object containing custom properties. Strings, numbers and booleans are the only supported format that can be passed to metadata. The metadata is limited to 4KB in size. | [optional] |