key property
      
      String
      get
      key
      
    
    
Key to compare DataSource
Implementation
String get key {
  String? result = "";
  if (uri != null && uri!.isNotEmpty) {
    result = uri;
  } else if (package != null && package!.isNotEmpty) {
    result = "$package:$asset";
  } else {
    result = asset;
  }
  if (formatHint != null) {
    result = "$result:$rawFormalHint";
  }
  return result!;
}