@Override
public Skill update(Skill skill) {
    List<Skill> currentSkills = this.service.getItemsFromFile(Skill.class);
    AtomicBoolean wasUpdated = new AtomicBoolean(false);

    currentSkills = currentSkills.stream()
        .map(s -> {
            if (Objects.equals(s.getId(), skill.getId())) {
                wasUpdated.set(true);
                return skill;
            }
            return s;
        })
        .collect(Collectors.toList());

    this.service.addItemsToFile(currentSkills);
    return wasUpdated.get() ? skill : null;
}