hashCode

{@return the hash code value for this bit set}

The hash code depends only on which bits are set within this BitSet.

The hash code is defined to be the result of the following calculation:

 `public int hashCode() {
long h = 1234;
long[] words = toLongArray();
for (int i = words.length; --i >= 0; )
h ^= words[i] * (i + 1);
return (int)((h >> 32) ^ h);
}`

Note that the hash code changes if the set of bits is altered.