@EnableDracarysChain
@SpringBootApplication
public class Application {

	public static void main(String[] args) {
		SpringApplication.run(JobRunrApplication.class, args);
	}

}

import lombok.RequiredArgsConstructor;
import org.springframework.stereotype.Component;

@RequiredArgsConstructor
@Component
public class UserValidateCmd implements Command {

	private final ValidationService validationService;

	public ChainContext execute(ChainContext ctx, Chain chain) {
		var event = ctx.getEvent(ValidateUserRequest.class);
		boolean response = validationService.validate(event);
		if (response) {
			return chain.proceed(ctx);
		}
		return ctx;
	}

}

@RequiredArgsConstructor
@Component
public class UserCreateCmd implements Command {

	private final UserRepository userRepository;

	public ChainContext execute(ChainContext ctx, Chain chain) {
		var event = ctx.getEvent(UserRequest.class);
		userRepository.create(event);
		return chain.proceed(ctx);
	}

}

@RequiredArgsConstructor
@Component
public class EmailSendCmd implements Command {

	private final EmailService emailService;

	public ChainContext execute(ChainContext ctx, Chain chain) {
		var event = ctx.getEvent(MailRequest.class);
		emailService.send(event);
		return chain.proceed(ctx);
	}

}

import ChainBase;
import org.springframework.stereotype.Component;

@Component
public class UserRegistrationChain extends ChainBase {

    @Override
    protected Class<?>[] getCommands() {
        return new Class<?>[]{UserValidateCmd.class, UserCreateCmd.class, EmailSendCmd.class};
    }
}