Find by name, extract salary and compute max in java, no streams

FindExtractMaxNoStreams.java

public Optional<Double> max(Collection<Double> collection) {
    if (collection == null || collection.isEmpty()) return Optional.empty();
    Iterator<Double> iter = collection.iterator();

    Double max = iter.next();
    while (iter.hasNext()) {
        Double n = iter.next();
        if (n > max) max = n;
    }

    return Optional.of(max);
}

public Collection<Employee> findName(Collection<Employee> collection, String name) {
    List<Employee> list = new ArrayList<>();
    if (collection == null || collection.isEmpty()) return list;
    for (Employee e : collection) {
        if (e.firstName.equals(name)) list.add(e);
    }
    return list;
}

public Collection<Double> extract(Collection<Employee> collection) {
    Collection<Double> list = new ArrayList<>();
    if (collection == null || collection.isEmpty()) return list;
    for (Employee e : collection) {
        list.add(e.salary);
    }
    return list;
}

// usage
double sal = max(extract(findName(collection, "Bob")));