Find elements, map and extract in java using streams

FindExtractMaxStreams.java

public Optional<Double> findExtractAndMax(Collection<Employee> collection, String name) {
    return collection.stream().filter(e -> e.firstName.equals(name)).map(e -> e.salary).max((a, b) -> (int) Math.signum(a - b));
}

//usage
double sal = findExtractAndMax(collection, "Bob");