public static Seconds secondsBetween(ReadableInstant start, ReadableInstant end) {
        int amount = BaseSingleFieldPeriod.between(start, end, DurationFieldType.seconds());
        return Seconds.seconds(amount);
    }
public static Seconds secondsBetween ( ReadableInstant start , ReadableInstant end ) { int amount = BaseSingleFieldPeriod . between ( start , end , DurationFieldType . seconds ( ) ) ; return Seconds . seconds ( amount ) ; }
Creates a <code>Seconds</code> representing the number of whole seconds
between the two specified datetimes.

@param start  the start instant, must not be null
@param end  the end instant, must not be null
@return the period in seconds
@throws IllegalArgumentException if the instants are null or invalid