Java – creates a map from a list, where the key is part of the internal and external objects

Is it possible (in a simple way) to change it to java8 stream? (please don't comment / answer, if you want to tell me two better, instead of all loops should be changed to flow, this is not a point)

final Map<String,String> map = new HashMap<>();

for(final Person person: list) {
    for(final Internal internal: person.getInternals()) {
        final String key = person.getName() + internal.getKey();
        map.put(key,internal.getValue());
    }
}

The main problem is that I can't use flatmap because I will lose my previous information Each created key is unique

Solution

Then you can pass them through a pair (although I didn't compile it, the idea should be there)

list.stream()
    .flatMap(person -> person.getInternals()
                       .stream()
                       .map(internal -> 
                           Pair.of(person.getName() + internal.getKey(),internal.getValue()))
    .collect(Collectors.toMap(Pair::getLeft,Pair::getRight));