private static List<Integer> getBucketCount(int numColumns, int numBucketBits) {
        List<Integer> ret = new ArrayList<Integer>(numColumns);
        int cnt = getNumBuckets(numBucketBits) / numColumns;
        int rst = getNumBuckets(numBucketBits) % numColumns;
        for (int i = 0; i < numColumns; ++i) {
            ret.add(cnt + (i < rst ? 1 : 0));
        }
        return ret;
    }
This method returns a list that contains the distributions of the given number of buckets over the given number
of columns.

@param numColumns    The number of columns to distribute to.
@param numBucketBits The number of bits to use for bucket id.
@return The bucket distribution.
document/src/main/java/com/yahoo/document/BucketDistribution.java