Implement code to monitor file delete action

I have this Java code which I want to use to monitor file changes into directory:

import com.validation.database.entity.EntityImportRequestsTable;
import com.validation.database.service.EntityImportRequestsService;
import org.springframework.context.event.ContextRefreshedEvent;
import org.springframework.context.event.EventListener;
import org.springframework.stereotype.Component;

import java.io.IOException;
import java.nio.file.*;
import java.time.Duration;
import java.time.Instant;
import java.util.HashMap;
import java.util.List;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;

private static String folderPath = "D:\\Import";

public static void main(final String[] args) throws IOException, InterruptedException {

        System.out.println("Running file verifier");
        System.out.println("monitoring folder " + folderPath);
        EntityImportRequestsJob sql = new EntityImportRequestsJob();

        WatchService watchService = FileSystems.getDefault().newWatchService();
        Path path = Paths.get(folderPath);
        path.register(watchService, StandardWatchEventKinds.ENTRY_CREATE, StandardWatchEventKinds.ENTRY_DELETE, StandardWatchEventKinds.ENTRY_MODIFY);
        WatchKey key;
        while ((key = watchService.take()) != null) {
            for (WatchEvent<?> event : key.pollEvents()) {
                System.out.println("Event kind:" + event.kind() + ". File affected: " + event.context() + ".");
                if(event.kind().equals(StandardWatchEventKinds.ENTRY_DELETE)){
                    Instant start = Instant.now();

                    boolean flag = true;

                    while(flag) {
                        while ((key = watchService.take()) != null) {
                            HashMap<String, List> map = sql.checkFileImport();

                            List values = map.get(event.context()); // get values by file name
                            if(values.contains("Completed")){
                                // exit the monitoring while loop
                                flag = false;
                            }
                        }
                        Thread.sleep(1000);
                    }

                    Instant end = Instant.now();
                    System.out.println(Duration.between(start,end));

                    long seconds = TimeUnit.MILLISECONDS.toSeconds(Duration.between(start,end).getSeconds());
                    long minutes = TimeUnit.MILLISECONDS.toMinutes(Duration.between(start,end).getSeconds());

                    System.out.format("Execution time %d minutes %d seconds", minutes, seconds);


                }

            }
            key.reset();
        }

        watchService.close();
    }

How I can improve this code in order properly to track file import time?