I have source and target classes that look like this

class UserHistorySource {
   private DetailsSource details;
}

and

class DetailsSource {

   private List<BalanceSource> balance;
   private List<RewardsSource> rewards;
   private List<LogsSource> logs;
   ….
   ….
}


class BalanceSource {

private String userId;
private OffsetDateTime datetime;
private String amount;

}


class RewardsSource {

private String userId;
private OffsetDateTime datetime;
private String amount;

}

class LogsSource {

private String userId;
private OffsetDateTime datetime;
private String amount;

}

Target Classes:

class UserHistoryTarget {
  private DetailsTarget details;
}

class DetailsTarget {

  private List<BalanceTarget> balance;
  private List<RewardsTarget> rewards;
  private List<LogsTarget> logs;
  ….
  ….
}


class BalanceTarget {

  private String userId;
  private String datetime;
  private String amount;
}


class RewardsTarget {
  private String userId;
  private String datetime;
  private String amount;
}

class LogsTarget {

  private String userId;
  private String datetime;
  private String amount;
}

The datetime in target classes are of type string while in source are of OffsetDateTime.
I could potentially create indivisual mapper files for Details, Balance, Rewards and Logs and implement a default method to convert the OffsetDateTime to String but I want to avoid writting mapper files for each class, is there a better way to do this ?