(java) Mapping utitlity to up/downcast or map to objects with similar fields

MappingUtil.java

package utils;

import com.google.gson.Gson;

public class MappingUtil {
    static Gson gson = new Gson();


    /**
     * Object down/up casting via json
     *
     * Will map all similar fields from one object to another
     *
     *
     * Example:
     *      BookingInput b = new BookingInput() //or load this in via a controller action param so that user fills in data
     *
     *      //now we want to enrich the object with the relevant data which users must not tamper
     *      Booking booking = MappingUtil.map(b, Booking.class);
     *      booking.bookingNumber = bookingNumber;
     *      booking.bookingCreatedAt = at;

     *
     * The price penalty measured for BookingInput => Booking: 3444ms for 10,000 objects
     * @param input the input object to map from
     * @param outputClass which class to map into.
     *
     */
    public static <T> T map(Object input, Class<T> outputClass) {
        String json = gson.toJson(input);
        return gson.fromJson(json, outputClass);
    }
}