Annotation constructor
      
      Annotation({ 
    
    
- CustomEmojiMetadata? customEmojiMetadata,
- int? length,
- RichLinkMetadata? richLinkMetadata,
- SlashCommandMetadata? slashCommand,
- int? startIndex,
- String? type,
- UserMentionMetadata? userMention,
Implementation
Annotation({
  this.customEmojiMetadata,
  this.length,
  this.richLinkMetadata,
  this.slashCommand,
  this.startIndex,
  this.type,
  this.userMention,
});