code: void insertEntry(int entryIndex, @Nullable K key, @Nullable V value, int hash) {
      this.entries[entryIndex] = ((long) hash << 32) | (NEXT_MASK & UNSET);
      this.keys[entryIndex] = key;
      this.values[entryIndex] = value;
    }
docs: Creates a fresh entry with the specified object at the specified position in the entry arrays.