Correctly implementing Zoned Date/Time in distributed System with Java.

MeetingApplication.java

import java.time.Instant;
import java.time.LocalDateTime;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;

public class MeetingApplication {

  public static void main(String[] args) {
    
    DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");

    /*
      1. Mohamed (who is in the "Europe/Belgrade" timezone) is creating a meeting slot with Duke in San Francisco.
    */

    // Mohamed meeting date and time
    String mohamedTime = "2022-07-10 10:30:00";

    // Mohamed Time Zone
    ZoneId mohamedZone = ZoneId.of("Europe/Belgrade");

    // Creating the meeting
    ZonedDateTime parsed = LocalDateTime.parse(mohamedTime, formatter).atZone(mohamedZone);

    System.out.println("1. Mohamed Booked a meeting according to his timezone at: " + parsed);
    // will print: 2022-07-10T10:30+02:00[Europe/Belgrade]

    // 2. Send the calendar invite and save the event
    Instant instant = parsed.toInstant();

    // Invitation (instant) is stored in the DB
    System.out.println("2. Mohamed Meeting time saved in database as UTC equivalent: " + instant);
    // will print: 2022-07-10T08:30:00Z

    /*
      Duke (in the "USA/San Francisco" timezone) is viewing the meeting DateTime Mohamed has booked to determine when exactly the meeting is.
    */

    // Initialize Duke timezone.
    ZoneId dukeZone = ZoneId.of("America/Los_Angeles");

    // The meeting time is retrieved from the database (instant) with Duke's timezone.
    ZonedDateTime dukeTime = ZonedDateTime.ofInstant(instant, dukeZone);

    System.out.println("3.1. Duke meeting will be at (formatted): " + dukeTime.format(formatter));
    // will print: 2022-07-10 01:30:00

    System.out.println("3.2. Duke meeting will be at: " + dukeTime);
    // will print: 2022-07-10T01:30-07:00[America/Los_Angeles]

    // Mohamed would like to make sure of the meeting time
    System.out.println("4. Again Mohamed is checking the meeting time: " + ZonedDateTime
            .ofInstant(instant, mohamedZone)
            .format(formatter)); // will print: 2022-07-10 10:30:00
  }
}