src/main/java/pta/de/core/common/GsonUTCDateAdapter.java

package pta.de.core.common;

import com.google.gson.*;

import java.lang.reflect.Type;
import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;
import java.util.TimeZone;

public class GsonUTCDateAdapter implements JsonSerializer<Date>, JsonDeserializer<Date> {

    private final DateFormat dateFormat;

    public GsonUTCDateAdapter() {
        dateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'", Locale.US);      //This is the format I need
        dateFormat.setTimeZone(TimeZone.getTimeZone("UTC"));                               //This is the key line which converts the date to UTC which cannot be accessed with the default serializer
    }

    @Override
    public synchronized JsonElement serialize(Date date, Type type, JsonSerializationContext jsonSerializationContext) {
        return new JsonPrimitive(dateFormat.format(date));
    }

    @Override
    public synchronized Date deserialize(JsonElement jsonElement, Type type, JsonDeserializationContext jsonDeserializationContext) {
        try {
            return dateFormat.parse(jsonElement.getAsString());
        } catch (ParseException e) {
            throw new JsonParseException(e);
        }
    }
}