如何获取spring boot中具有角色的所有用户的列表？

import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.security.core.userdetails.UserDetailsService;
import org.springframework.security.core.userdetails.UsernameNotFoundException;
import org.springframework.stereotype.Service;

@Service
public class CustomUserDetailsService implements UserDetailsService {

    private final UserRepository userRepository;

    public CustomUserDetailsService(UserRepository userRepository) {
        this.userRepository = userRepository;
    }

    @Override
    public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {
        User user = userRepository.findByUsername(username);
        if (user == null) {
            throw new UsernameNotFoundException("User not found");
        }
        return new CustomUserDetails(user);
    }
}

import org.springframework.security.core.GrantedAuthority;
import org.springframework.security.core.userdetails.User;

import java.util.Collection;

public class CustomUserDetails extends User {

    private final User user;

    public CustomUserDetails(User user) {
        super(user.getUsername(), user.getPassword(), user.getAuthorities());
        this.user = user;
    }

    public String getRole() {
        // 返回用户的角色信息
        return user.getRole();
    }
}

@Service
public class UserService {

    private final CustomUserDetailsService userDetailsService;

    public UserService(CustomUserDetailsService userDetailsService) {
        this.userDetailsService = userDetailsService;
    }

    public List<String> getUsersWithRole(String role) {
        List<String> users = new ArrayList<>();
        for (UserDetails userDetails : userDetailsService.loadUserByUsername("admin").getAuthorities()) {
            if (userDetails.getAuthority().equals(role)) {
                users.add(userDetails.getUsername());
            }
        }
        return users;
    }
}