code: public static long randomLong(long startInclusive, long endExclusive) {
      checkArgument(startInclusive <= endExclusive, "End must be greater than or equal to start");
      if (startInclusive == endExclusive) {
        return startInclusive;
      }
      return RANDOM.longs(1, startInclusive, endExclusive).sum();
    }
docs: Returns a random long within the specified range.
  
  @param startInclusive the earliest long that can be returned
  @param endExclusive the upper bound (not included)
  @return the random long
  @throws IllegalArgumentException if endExclusive is less than startInclusive