@SafeVarargs
    static <T> Seq<T> concat(Optional<? extends T>... optionals) {
        if (optionals == null)
            return null;

        return Seq.of(optionals).filter(Optional::isPresent).map(Optional::get);
    }
Concatenate a number of optionals.
<p>
<pre><code>
// (1, 2)
Seq.concat(Optional.of(1), Optional.empty(), Optional.of(2))
</code></pre>
jOOL/src/main/java/org/jooq/lambda/Seq.java