How to convert Map value using stream

Issue

I have task: Return a map of companies, where the key is its name and the value is a list of employees stored as String consisting of firstName and lastName separated by space. Here is my solution and its works fine:

    Map<String, List<String>> getUserPerCompanyAsString() {
        return getCompanyStream()
                .collect(Collectors.toMap(Company::getName, company ->  getUserNames(company.getUsers())));
    }

    private List<String> getUserNames(List<User> users) {
        return users.stream()
                .map(user -> user.getFirstName() + " " + user.getLastName())
                .collect(Collectors.toList());
    }

public class Company {
    private final String name;
    private final List<User> users;
}

public class User {
    private final String firstName;
    private final String lastName;
    private final Sex sex;
    private final int age;
    private final List<Account> accounts;
    private final List<Permit> permits;
}

So my question, how to convert List<User> as map value to List<String> with firstName and lastName separated by space in one stream chain without helper method?

Solution

Solution

Thanks to Thomas suggestion I'm able solve this problem without helper method:

    Map<String, List<String>> getUserPerCompanyAsString() {
        return getCompanyStream()
                .collect(Collectors.toMap(Company::getName, company -> company.getUsers().stream()
                                .map(user -> user.getFirstName() + " " + user.getLastName())
                                .collect(Collectors.toList())));

Answered By - Fleckinger