Google Calendar API Error?

Question

I tried to get the Free Time slots from the Google calendar API using android studio.

MainActivity.java(Part of code)

This is i tried code for get the Free Time slots.

           private List<String> getDataFromApi() throws IOException {
    //             List the next 10 events from the primary calendar.

            DateTime startDate = new DateTime(System.currentTimeMillis());
            DateTime endDate = new DateTime(System.currentTimeMillis()+24 * 60 * 60 * 1000);

            org.joda.time.DateTime startDateJoda= new org.joda.time.DateTime(startDate);
            org.joda.time.DateTime endDateJoda= startDateJoda.plusHours(24);

            List<String> eventStrings = new ArrayList<String>();
            List<String> tests = new ArrayList<String>();

            DateTime rootStart = startDate;
            DateTime rootEnd = endDate;

            org.joda.time.DateTime rootStartJoda = new  org.joda.time.DateTime(rootStart);
            org.joda.time.DateTime rootEndJoda = new  org.joda.time.DateTime(rootEnd);

            Events events = mService.events().list("primary")
                    .setMaxResults(10)
                    .setTimeMin(startDate)
                    .setTimeMax(endDate)
                    .setOrderBy("startTime")
                    .setSingleEvents(true)
                    .execute();


            List<Event> items = events.getItems();

            int interval = 2 ; // how big single slot should be (in this case 2 hrs)

            ArrayList<MyEvent> freeSlots = new ArrayList<MyEvent>();
            for (int index =0;index<items.size();index++) {
                Event event = items.get(index);

                DateTime eventStart = event.getStart().getDateTime();
                org.joda.time.DateTime eventStartJoda= new org.joda.time.DateTime(eventStart);
                DateTime eventEnd = event.getEnd().getDateTime();
                org.joda.time.DateTime eventEndJoda= new org.joda.time.DateTime(eventEnd);

                if (index == 0 && startDateJoda.isBefore(eventStartJoda) ) {
                    freeSlots.add( new MyEvent(startDateJoda,eventEndJoda) );
                }
                else if (index == 0) {
                    startDate = event.getEnd().getDateTime();
                    org.joda.time.DateTime startDatejoda=new org.joda.time.DateTime(startDate);
                }
//                else if (new org.joda.time.DateTime(events.get(index - 1).getEnd().getDateTime()).isBefore(eventStartJoda)==-1) {
//                    freeSlots.add(new MyEvent
//                            (new org.joda.time.DateTime(items.get(index - 1).getEnd().getDateTime()) ,eventStartJoda));
//                }

                if (items.size() == (index + 1) && new org.joda.time.DateTime(event.getEnd().getDateTime()).isBefore(endDateJoda)) {
                    freeSlots.add(new MyEvent(eventEndJoda, endDateJoda));
                }
            }
            if (items.size() == 0) {
                freeSlots.add(new MyEvent(startDateJoda,endDateJoda));
            }

            ArrayList<MyEvent> hourSlots = new ArrayList<MyEvent>();
            MyEvent temp = null;
            for(int index =0;index<freeSlots.size();index++){
                MyEvent free = (MyEvent) freeSlots.get(index);

                int freeHours = free.endDate.getHourOfDay()- free.startDate.getHourOfDay();
                org.joda.time.DateTime freeStart = free.startDate, freeEnd = free.endDate;
                while(freeStart.getHourOfDay()+freeHours+interval>=0) { // 11 + 4 + 2 >= 0
                    if(freeHours>=interval) {
                        temp.startDate = free.startDate;
                        temp.endDate= temp.endDate.hourOfDay().setCopy(temp.endDate.getHourOfDay()+freeHours);
                        temp.startDate = free.startDate;
                        temp.startDate = temp.startDate.hourOfDay().setCopy(temp.startDate.getHourOfDay()+freeHours-interval);
                        if(temp.startDate.getHourOfDay() >= rootStartJoda.getHourOfDay() && temp.endDate.getHourOfDay() <= rootEndJoda.getHourOfDay()) {
                            hourSlots.add(new MyEvent(temp.startDate,temp.endDate));
                            temp = null;
                        }
                    }
                    freeHours--;
                }
            }

            List<MyEvent> FreeList = new ArrayList<MyEvent>();
            for (MyEvent events2: FreeList) {
                org.joda.time.DateTime start = events2.startDate;
                org.joda.time.DateTime end = events2.endDate;
                if (start == null) {
                    start = events2.startDate;
                    end   =  events2.endDate;
                }
                eventStrings.add(
                        String.format("(%s) - (%s)", start,end));
            }

            return eventStrings;
        }

MyEvent.java

This is the class i get the events.

public class MyEvent implements Comparable<MyEvent> {
    public DateTime startDate; // org.joda.time.DateTime
    public DateTime endDate; // org.joda.time.DateTime

    public MyEvent(DateTime startDate, DateTime endDate) {
        this.startDate = startDate;
        this.endDate = endDate;
    }
    /**
     *
     * @param  anotherEvent
     * @return 0 for same time, 1 : this>anotherEvent, -1 : this<anotherEvent
     */
    @Override
    public int compareTo(@NonNull MyEvent anotherEvent) {
        // implement 0/1/-1 based on your DateTime object

        return 0;
    }
}

For this code i get this Error.

No instant converter found for type: com.google.api.client.util.DateTime

What is the reason for that?

Glad if anyone can help

Thank You