https://spring.io/guides/gs/scheduling-tasks/

https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/scheduling/annotation/Scheduled.html

2021
https://reflectoring.io/spring-scheduler/
    https://habr.com/ru/post/580062/
    https://github.com/thombergs/code-examples/tree/master/spring-boot/spring-boot-scheduler
DevmarkRu - Scheduler in Spring ru of 10:14
    https://www.youtube.com/watch?v=gJbhPjNSm9k
2020
https://spring.io/blog/2020/11/10/new-in-spring-5-3-improved-cron-expressions
2019
SpringAcademy - Spring Boot @Scheduled Crash Course of 14:20
    https://www.youtube.com/watch?v=92-qLIxv0JA

at main app
import org.springframework.scheduling.annotation.EnableScheduling;
    @EnableScheduling
    https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/scheduling/annotation/EnableScheduling.html
    
later...
    @Scheduled(initialDelay = ONE_SECOND, fixedDelay = ONE_MINUTE)

samples