static <T, K, V> Map<K, V> toMap(Stream<Tuple2<K, V>> stream) {
        return stream.collect(Collectors.toMap(Tuple2::v1, Tuple2::v2));
    }
Collect a Stream of {@link Tuple2} into a Map.
jOOL-java-8/src/main/java/org/jooq/lambda/Seq.java