@Override
    public void putAll(Map<? extends Byte, ? extends V> sourceMap) {
        if (sourceMap instanceof ByteObjectHashMap) {
            // Optimization - iterate through the arrays.
            @SuppressWarnings("unchecked")
            ByteObjectHashMap<V> source = (ByteObjectHashMap<V>) sourceMap;
            for (int i = 0; i < source.values.length; ++i) {
                V sourceValue = source.values[i];
                if (sourceValue != null) {
                    put(source.keys[i], sourceValue);
                }
            }
            return;
        }

        // Otherwise, just add each entry.
        for (Entry<? extends Byte, ? extends V> entry : sourceMap.entrySet()) {
            put(entry.getKey(), entry.getValue());
        }
    }
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