protected int hashIndex(int hashCode, int dataSize) {
        return hashCode & (dataSize - 1);
    }
Gets the index into the data storage for the hashCode specified.
This implementation uses the least significant bits of the hashCode.
Subclasses can override this to return alternate bucketing.

@param hashCode the hash code to use
@param dataSize the size of the data to pick a bucket from
@return the bucket index
jphp-runtime/src/php/runtime/common/collections/map/AbstractHashedMap.java