@Override
    public Optional<Map.Entry<K, V>> findFirst() {
        return inner.findFirst();
    }
Returns an {@link Optional} describing the first element of this stream,
or an empty {@code Optional} if the stream is empty.  If the stream has
no encounter order, then any element may be returned.
<p>
This is a short-circuiting terminal operation.

@return  an {@code Optional} describing the first element of this stream,
         or an empty {@code Optional} if the stream is empty

@throws NullPointerException if the element selected is null
common-parent/mapstream/src/main/java/com/speedment/common/mapstream/MapStream.java