| Name | Type | Description | Notes |
|---|---|---|---|
| fromUserId | String | Sender user ID. | |
| messageType | String | Message type. Supports built-in types and custom types registered in the client SDK. Custom types must not start with `RC:` and must not exceed 32 characters. | |
| content | String | Broadcast message payload serialized as a string. Maximum size is 128 KB. | |
| isEchoToSender | Integer | Whether to sync the broadcast message to the sender's client while the sender is online. | [optional] |