Create a class extending JsonSerializer and then on your getter use the @JsonSerialize(using=MySerializer.class) annotation
One of the serializer could be something like:
public class MySerializer extends JsonSerializer<String> {
@Override
public void serialize( String value
, JsonGenerator jgen
, SerializerProvider provider) throws IOException
, JsonProcessingException {
jgen.writeString(MyUtilsClass.formatWithHyphen(value) );
}
}