public static <T extends Comparable<? super T>> Collector<T, ?, OptionalLong> minIndex() {
        return minIndex(Comparator.naturalOrder());
    }
public static < T extends Comparable < ? super T > > Collector < T , ? , OptionalLong > minIndex ( ) { return minIndex ( Comparator . naturalOrder ( ) ) ; }
Returns a {@code Collector} which finds the index of the minimal stream
element according to the elements natural order. If there are several
minimal elements, the index of the first one is returned.

@param <T> the type of the input elements
@return a {@code Collector} which finds the index of the minimal element.
@see #minIndex(Comparator)
@since 0.3.5