Fix HA User Typing bug (#4273)

model/websocket_message.go

@@ -36,7 +36,7 @@ type WebSocketMessage interface {
 }
 
 type WebsocketBroadcast struct {
-	OmitUsers map[string]bool `json:"-"`          // broadcast is omitted for users listed here
+	OmitUsers map[string]bool `json:"omit_users"` // broadcast is omitted for users listed here
 	UserId    string          `json:"user_id"`    // broadcast only occurs for this user
 	ChannelId string          `json:"channel_id"` // broadcast only occurs for users in this channel
 	TeamId    string          `json:"team_id"`    // broadcast only occurs for users in this team