code: public LongStream longs(long streamSize) {
          if (streamSize < 0L)
              throw new IllegalArgumentException(BAD_SIZE);
          return StreamSupport.longStream
              (new RandomLongsSpliterator
               (0L, streamSize, Long.MAX_VALUE, 0L),
               false);
      }
docs: Returns a stream producing the given {@code streamSize} number of
  pseudorandom {@code long} values.
  
  @param streamSize the number of values to generate
  @return a stream of pseudorandom {@code long} values
  @throws IllegalArgumentException if {@code streamSize} is
  less than zero
  @since 1.8