@Override
    public Set<Entry<K, V>> entrySet() {
        if (size == 0) {
            return Collections.emptySet();
        }
        Set<Entry<K, V>> set = CollectionUtil.newSetWithExpectedSize(size);
        for (int i = 0, length = values.length; i < length; i++) {
            V element = values[i];
            if (element != null) {
                set.add(Map.entry(keys[i], element));
            }
        }
        return set;
    }
@author James Chen
@see java.util.EnumMap
turms-server-common/src/main/java/im/turms/server/common/infra/collection/FastEnumMap.java