@Override
    public <K, V> Map<K, V> toMap(Function<? super T, ? extends K> keyMapper, Function<? super T, ? extends V> valueMapper) {
        return Seq.toMap(this, keyMapper, valueMapper);
    }
Always returns false. Seq streams are always sequential and, as such,
doesn't support parallelization.

@return false
@see <a href="https://github.com/jOOQ/jOOL/issues/130">jOOL Issue #130</a>
jOOL-java-8/src/main/java/org/jooq/lambda/SeqImpl.java