PhonebookWrapper savePersons

Observable personsObs =
              Observable
                .from(personList)
                .reduce(new ArrayList<Person>(), (acc, person) -> {
                      person.setInPhonebook(isInPhonebook);
                      person.setAccessoryType(accessoryType);
                      acc.add(person);
                      return acc;
                })
                .map(personDao::save);
        
        Observable contactsObs =
                Observable
                        .from(personList)
                        .reduce(new ArrayList<Contact>(), (acc, person) -> {
                            for (Contact contact : person.getContacts()) {
                                contact.setPersonId(person.getId());
                                contact.setAccessoryType(person.getAccessoryType());
                            }
                            return acc;
                        })
                        .map(contacts -> contactDao.save(contacts).asRxCompletable());

        return Observable.merge(personsObs, contactsObs).toCompletable();