CometChatMessageHeader constructor
      const
      CometChatMessageHeader({ 
    
    
- Key? key,
- WidgetBuilder? backButton,
- MessageHeaderStyle messageHeaderStyle = const MessageHeaderStyle(),
- Group? group,
- User? user,
- List<Widget> ? appBarOptions(- User? user,
- Group? group,
- BuildContext context
 
- Widget listItemView(- Group? group,
- User? user,
- BuildContext context
 
- bool? hideBackButton = true,
- bool? disableUserPresence,
- Widget? privateGroupIcon,
- Widget? protectedGroupIcon,
- Widget? subtitleView(- Group? group,
- User? user,
- BuildContext context
 
- Widget? chatMessagesHeader({})?,
- CometChatTheme? theme,
- AvatarStyle? avatarStyle,
- StatusIndicatorStyle? statusIndicatorStyle,
- ListItemStyle? listItemStyle,
- Widget? chatAvatar({})?,
- bool disableTyping = false,
- VoidCallback? onBack,
Implementation
const CometChatMessageHeader(
    {super.key,
    this.backButton,
    this.messageHeaderStyle = const MessageHeaderStyle(),
    this.group,
    this.user,
    this.appBarOptions,
    this.listItemView,
    this.hideBackButton = true,
    this.disableUserPresence,
    this.privateGroupIcon,
    this.protectedGroupIcon,
    this.subtitleView,
    this.chatMessagesHeader,
    this.theme,
    this.avatarStyle,
    this.statusIndicatorStyle,
    this.listItemStyle,
    this.chatAvatar,
    this.disableTyping = false,
    this.onBack})
    : assert(user != null || group != null,
          "One of user or group should be passed"),
      assert(user == null || group == null,
          "Only one of user or group should be passed");