anchor.diff:      logger.stdout('Migrating ${options.directory}');
       logger.stdout('');
   
  +    if (!MigrateCommand.nullSafetyOnByDefault) {
  +      logger.stdout(MigrateCommand.preFlagFlipCaveat);
  +      logger.stdout('');
  +    }
  +
  +    logger.stdout(MigrateCommand.migrationGuideLink);
  +    logger.stdout('');
  +
       if (hasMultipleAnalysisContext) {
  -      logger
  -          .stdout('Note: more than one project found; migrating the top-level '
  -              'project.');
  +      logger.stdout('Note: more than one project found; migrating the '
  +          'top-level project.');
         logger.stdout('');
       }
   
  
positive.code:   }
  
    @override
    String get description => cmdDescription;
  
    @override
    String get invocation {
  
negative.code:   static const String cmdName = 'migrate';
  
    static const String cmdDescription =
        'Perform a null safety migration on a project or package.';
  
    static const String migrationGuideLink =
        'See https://dart.dev/go/null-safety-migration for a migration guide.';
  
    static const String preFlagFlipCaveat =
        'Note: this tool is currently running on an SDK version where null '
        'safety is not yet enabled by default. You may encounter issues in the '
        'migration process - some aspects of the toolchain assume that they are '
        'running on an SDK where null safety has been enabled by default.';
  
    /// Return whether the SDK has null safety on by default.
    static bool get nullSafetyOnByDefault => IsEnabledByDefault.non_nullable;
  
    final bool verbose;
  
  