@Override
    public int hashCode() {
        // Hashcode is based on all non-zero, valid keys. We have to scan the whole keys
        // array, which may have different lengths for two maps of same size(), so the
        // capacity cannot be used as input for hashing but the size can.
        int hash = size;
        for (byte key : keys) {
            // 0 can be a valid key or unused slot, but won't impact the hashcode in either case.
            // This way we can use a cheap loop without conditionals, or hard-to-unroll operations,
            // or the devastatingly bad memory locality of visiting value objects.
            // Also, it's important to use a hash function that does not depend on the ordering
            // of terms, only their values; since the map is an unordered collection and
            // entries can end up in different positions in different maps that have the same
            // elements, but with different history of puts/removes, due to conflicts.
            hash ^= hashCode(key);
        }
        return hash;
    }
The load factor for the map. Used to calculate {@link #maxSize}.
jraft-rheakv/rheakv-core/src/main/java/com/alipay/sofa/jraft/rhea/util/ByteObjectHashMap.java