content: package org.aion.util.map;
  
  import java.io.IOException;
  import java.io.InvalidObjectException;
  import java.io.Serializable;
  import java.lang.reflect.ParameterizedType;
  import java.lang.reflect.Type;
  import java.util.AbstractCollection;
  import java.util.AbstractSet;
  import java.util.Collection;
  import java.util.ConcurrentModificationException;
  import java.util.Iterator;
  import java.util.Map;
  import java.util.NoSuchElementException;
  import java.util.Objects;
  import java.util.Set;
  import java.util.Spliterator;
  import java.util.function.BiConsumer;
  import java.util.function.BiFunction;
  import java.util.function.Consumer;
  import java.util.function.Function;
  
  /**
   * Don't use this hashmap class without override their hash() function. This class is abstract to
   * prevent use it directly.
   *
   * @author jin
   * @param <K>
   * @param <V>
   */
  public abstract class HashMap<K, V> extends AbstractMap<K, V>
          implements Map<K, V>, Cloneable, Serializable {
  
      private static final long serialVersionUID = 362498820763181266L;
  
      /*
       * Implementation notes.
       *
       * This map usually acts as a binned (bucketed) hash table, but
       * when bins get too large, they are transformed into bins of
       * TreeNodes, each structured similarly to those in
       * java.util.TreeMap. Most methods try to use normal bins, but
       * relay to TreeNode methods when applicable (simply by checking
       * instanceof a node).  Bins of TreeNodes may be traversed and
       * used like any others, but additionally support faster lookup
       * when overpopulated. However, since the vast majority of bins in
       * normal use are not overpopulated, checking for existence of
       * tree bins may be delayed in the course of table methods.
       *
       * Tree bins (i.e., bins whose elements are all TreeNodes) are
       * ordered primarily by hashCode, but in the case of ties, if two
       * elements are of the same "class C implements Comparable<C>",
       * type then their compareTo method is used for ordering. (We
       * conservatively check generic type via reflection to validate
       * this -- see method comparableClassFor).  The added complexity
       * of tree bins is worthwhile in providing worst-case O(log n)
       * operations when keys either have distinct hashes or are
       * orderable, Thus, performance degrades gracefully under
       * accidental or malicious usages in which hashCode() methods
       * return values that are poorly distributed, as well as those in
       * which many keys share a hashCode, so long as they are also
       * Comparable. (If neither of these apply, we may waste about a
       * factor of two in time and space compared to taking no
       * precautions. But the only known cases stem from poor user
       * programming practices that are already so slow that this makes
       * little difference.)
       *
       * Because TreeNodes are about twice the size of regular nodes, we
       * use them only when bins contain enough nodes to warrant use
       * (see TREEIFY_THRESHOLD). And when they become too small (due to
       * removal or resizing) they are converted back to plain bins.  In
       * usages with well-distributed user hashCodes, tree bins are
       * rarely used.  Ideally, under random hashCodes, the frequency of
       * nodes in bins follows a Poisson distribution
       * (http://en.wikipedia.org/wiki/Poisson_distribution) with a
       * parameter of about 0.5 on average for the default resizing
       * threshold of 0.75, although with a large variance because of
       * resizing granularity. Ignoring variance, the expected
       * occurrences of list size k are (exp(-0.5) * pow(0.5, k) /
       * factorial(k)). The first values are:
       *
       * 0:    0.60653066
       * 1:    0.30326533
       * 2:    0.07581633
       * 3:    0.01263606
       * 4:    0.00157952
       * 5:    0.00015795
       * 6:    0.00001316
       * 7:    0.00000094
       * 8:    0.00000006
       * more: less than 1 in ten million
       *
       * The root of a tree bin is normally its first node.  However,
       * sometimes (currently only upon Iterator.remove), the root might
       * be elsewhere, but can be recovered following parent links
       * (method TreeNode.root()).
       *
       * All applicable internal methods accept a hash code as an
       * argument (as normally supplied from a public method), allowing
       * them to call each other without recomputing user hashCodes.
       * Most internal methods also accept a "tab" argument, that is
       * normally the current table, but may be a new or old one when
       * resizing or converting.
       *
       * When bin lists are treeified, split, or untreeified, we keep
       * them in the same relative access/traversal order (i.e., field
       * Node.next) to better preserve locality, and to slightly
       * simplify handling of splits and traversals that invoke
       * iterator.remove. When using comparators on insertion, to keep a
       * total ordering (or as close as is required here) across
       * rebalancings, we compare classes and identityHashCodes as
       * tie-breakers.
       *
       * The use and transitions among plain vs tree modes is
       * complicated by the existence of subclass LinkedHashMap. See
       * below for hook methods defined to be invoked upon insertion,
       * removal and access that allow LinkedHashMap internals to
       * otherwise remain independent of these mechanics. (This also
       * requires that a map instance be passed to some utility methods
       * that may create new nodes.)
       *
       * The concurrent-programming-like SSA-based coding style helps
       * avoid aliasing errors amid all of the twisty pointer operations.
       */
      /** The default initial capacity - MUST be a power of two. */
      static final int DEFAULT_INITIAL_CAPACITY = 1 << 4; // aka 16
  
      /**
       * The maximum capacity, used if a higher value is implicitly specified by either of the
       * constructors with arguments. MUST be a power of two <= 1<<30.
       */
      static final int MAXIMUM_CAPACITY = 1 << 30;
  
      /** The load factor used when none specified in constructor. */
      static final float DEFAULT_LOAD_FACTOR = 0.75f;
  
      /**
       * The bin count threshold for using a tree rather than list for a bin. Bins are converted to
       * trees when adding an element to a bin with at least this many nodes. The value must be
       * greater than 2 and should be at least 8 to mesh with assumptions in tree removal about
       * conversion back to plain bins upon shrinkage.
       */
      static final int TREEIFY_THRESHOLD = 8;
  
      /**
       * The bin count threshold for untreeifying a (split) bin during a resize operation. Should be
       * less than TREEIFY_THRESHOLD, and at most 6 to mesh with shrinkage detection under removal.
       */
      static final int UNTREEIFY_THRESHOLD = 6;
  
      /**
       * The smallest table capacity for which bins may be treeified. (Otherwise the table is resized
       * if too many nodes in a bin.) Should be at least 4 * TREEIFY_THRESHOLD to avoid conflicts
       * between resizing and treeification thresholds.
       */
      static final int MIN_TREEIFY_CAPACITY = 64;
  
      /**
       * Basic hash bin node, used for most entries. (See below for TreeNode subclass, and in
       * LinkedHashMap for its Entry subclass.)
       */
      static class Node<K, V> implements Map.Entry<K, V> {
  
          final int hash;
          protected final K key;
          V value;
          Node<K, V> next;
  
          Node(int hash, K key, V value, Node<K, V> next) {
              this.hash = hash;
              this.key = key;
              this.value = value;
              this.next = next;
          }
  
          public final K getKey() {
              return key;
          }
  
          public final V getValue() {
              return value;
          }
  
          public final String toString() {
              return key + "=" + value;
          }
  
          public final int hashCode() {
              return Objects.hashCode(key) ^ Objects.hashCode(value);
          }
  
          public final V setValue(V newValue) {
              V oldValue = value;
              value = newValue;
              return oldValue;
          }
  
          public boolean equals(Object o) {
              if (o == this) {
                  return true;
              }
              if (o instanceof Map.Entry) {
                  Map.Entry<?, ?> e = (Map.Entry<?, ?>) o;
                  if (Objects.equals(key, e.getKey()) && Objects.equals(value, e.getValue())) {
                      return true;
                  }
              }
              return false;
          }
      }
  
      /* ---------------- Static utilities -------------- */
      /**
       * Computes key.hashCode() and spreads (XORs) higher bits of hash to lower. Because the table
       * uses power-of-two masking, sets of hashes that vary only in bits above the current mask will
       * always collide. (Among known examples are sets of Float keys holding consecutive whole
       * numbers in small tables.) So we apply a transform that spreads the impact of higher bits
       * downward. There is a tradeoff between speed, utility, and quality of bit-spreading. Because
       * many common sets of hashes are already reasonably distributed (so don't benefit from
       * spreading), and because we use trees to handle large sets of collisions in bins, we just XOR
       * some shifted bits in the cheapest possible way to reduce systematic lossage, as well as to
       * incorporate impact of the highest bits that would otherwise never be used in index
       * calculations because of table bounds.
       */
      protected abstract int hash(Object key);
      //    static int hash(Object key) {
      //        int h;
      //        return (key == null) ? 0 : (h = key.hashCode()) ^ (h >>> 16);
      //    }
  
      protected abstract boolean keyEquals(Object key, K k);
  
      protected abstract boolean valEquals(Object value, V v);
  
      /** Returns x's Class if it is of the form "class C implements Comparable<C>", else null. */
      static Class<?> comparableClassFor(Object x) {
          if (x instanceof Comparable) {
              Class<?> c;
              Type[] ts, as;
              ParameterizedType p;
              if ((c = x.getClass()) == String.class) // bypass checks
              {
                  return c;
              }
              if ((ts = c.getGenericInterfaces()) != null) {
                  for (Type t : ts) {
                      if ((t instanceof ParameterizedType)
                              && ((p = (ParameterizedType) t).getRawType() == Comparable.class)
                              && (as = p.getActualTypeArguments()) != null
                              && as.length == 1
                              && as[0] == c) // type arg is c
                      {
                          return c;
                      }
                  }
              }
          }
          return null;
      }
  
      /** Returns k.compareTo(x) if x matches kc (k's screened comparable class), else 0. */
      @SuppressWarnings({"rawtypes", "unchecked"}) // for cast to Comparable
      static int compareComparables(Class<?> kc, Object k, Object x) {
          return (x == null || x.getClass() != kc ? 0 : ((Comparable) k).compareTo(x));
      }
  
      /** Returns a power of two size for the given target capacity. */
      static final int tableSizeFor(int cap) {
          int n = cap - 1;
          n |= n >>> 1;
          n |= n >>> 2;
          n |= n >>> 4;
          n |= n >>> 8;
          n |= n >>> 16;
          return (n < 0) ? 1 : (n >= MAXIMUM_CAPACITY) ? MAXIMUM_CAPACITY : n + 1;
      }
  
      /* ---------------- Fields -------------- */
      /**
       * The table, initialized on first use, and resized as necessary. When allocated, length is
       * always a power of two. (We also tolerate length zero in some operations to allow
       * bootstrapping mechanics that are currently not needed.)
       */
      transient Node<K, V>[] table;
  
      /** Holds cached entrySet(). Note that AbstractMap fields are used for keySet() and values(). */
      transient Set<Map.Entry<K, V>> entrySet;
  
      /** The number of key-value mappings contained in this map. */
      transient int size;
  
      /**
       * The number of times this HashMap has been structurally modified Structural modifications are
       * those that change the number of mappings in the HashMap or otherwise modify its internal
       * structure (e.g., rehash). This field is used to make iterators on Collection-views of the
       * HashMap fail-fast. (See ConcurrentModificationException).
       */
      transient int modCount;
  
      /**
       * The next size value at which to resize (capacity * load factor).
       *
       * @serial
       */
      // (The javadoc description is true upon serialization.
      // Additionally, if the table array has not been allocated, this
      // field holds the initial array capacity, or zero signifying
      // DEFAULT_INITIAL_CAPACITY.)
      int threshold;
  
      /**
       * The load factor for the hash table.
       *
       * @serial
       */
      final float loadFactor;
  
      /* ---------------- Public operations -------------- */
      /**
       * Constructs an empty {@code HashMap} with the specified initial capacity and load factor.
       *
       * @param initialCapacity the initial capacity
       * @param loadFactor the load factor
       * @throws IllegalArgumentException if the initial capacity is negative or the load factor is
       *     nonpositive
       */
      public HashMap(int initialCapacity, float loadFactor) {
          if (initialCapacity < 0) {
              throw new IllegalArgumentException("Illegal initial capacity: " + initialCapacity);
          }
          if (initialCapacity > MAXIMUM_CAPACITY) {
              initialCapacity = MAXIMUM_CAPACITY;
          }
          if (loadFactor <= 0 || Float.isNaN(loadFactor)) {
              throw new IllegalArgumentException("Illegal load factor: " + loadFactor);
          }
          this.loadFactor = loadFactor;
          this.threshold = tableSizeFor(initialCapacity);
      }
  
      /**
       * Constructs an empty {@code HashMap} with the specified initial capacity and the default load
       * factor (0.75).
       *
       * @param initialCapacity the initial capacity.
       * @throws IllegalArgumentException if the initial capacity is negative.
       */
      public HashMap(int initialCapacity) {
          this(initialCapacity, DEFAULT_LOAD_FACTOR);
      }
  
      /**
       * Constructs an empty {@code HashMap} with the default initial capacity (16) and the default
       * load factor (0.75).
       */
      public HashMap() {
          this.loadFactor = DEFAULT_LOAD_FACTOR; // all other fields defaulted
      }
  
      /**
       * Constructs a new {@code HashMap} with the same mappings as the specified {@code Map}. The
       * {@code HashMap} is created with default load factor (0.75) and an initial capacity sufficient
       * to hold the mappings in the specified {@code Map}.
       *
       * @param m the map whose mappings are to be placed in this map
       * @throws NullPointerException if the specified map is null
       */
      public HashMap(Map<? extends K, ? extends V> m) {
          this.loadFactor = DEFAULT_LOAD_FACTOR;
          putMapEntries(m, false);
      }
  
      /**
       * Implements Map.putAll and Map constructor
       *
       * @param m the map
       * @param evict false when initially constructing this map, else true (relayed to method
       *     afterNodeInsertion).
       */
      final void putMapEntries(Map<? extends K, ? extends V> m, boolean evict) {
          int s = m.size();
          if (s > 0) {
              if (table == null) { // pre-size
                  float ft = ((float) s / loadFactor) + 1.0F;
                  int t = ((ft < (float) MAXIMUM_CAPACITY) ? (int) ft : MAXIMUM_CAPACITY);
                  if (t > threshold) {
                      threshold = tableSizeFor(t);
                  }
              } else if (s > threshold) {
                  resize();
              }
              for (Map.Entry<? extends K, ? extends V> e : m.entrySet()) {
                  K key = e.getKey();
                  V value = e.getValue();
                  putVal(hash(key), key, value, false, evict);
              }
          }
      }
  
      /**
       * Returns the number of key-value mappings in this map.
       *
       * @return the number of key-value mappings in this map
       */
      public int size() {
          return size;
      }
  
      /**
       * Returns {@code true} if this map contains no key-value mappings.
       *
       * @return {@code true} if this map contains no key-value mappings
       */
      public boolean isEmpty() {
          return size == 0;
      }
  
      /**
       * Returns the value to which the specified key is mapped, or {@code null} if this map contains
       * no mapping for the key.
       *
       * <p>More formally, if this map contains a mapping from a key {@code k} to a value {@code v}
       * such that {@code (key==null ? k==null : key.equals(k))}, then this method returns {@code v};
       * otherwise it returns {@code null}. (There can be at most one such mapping.)
       *
       * <p>A return value of {@code null} does not <i>necessarily</i> indicate that the map contains
       * no mapping for the key; it's also possible that the map explicitly maps the key to {@code
       * null}. The {@link #containsKey containsKey} operation may be used to distinguish these two
       * cases.
       *
       * @see #put(Object, Object)
       */
      public V get(Object key) {
          Node<K, V> e;
          return (e = getNode(hash(key), key)) == null ? null : e.value;
      }
  
      /**
       * Implements Map.get and related methods
       *
       * @param hash hash for key
       * @param key the key
       * @return the node, or null if none
       */
      final Node<K, V> getNode(int hash, Object key) {
          Node<K, V>[] tab;
          Node<K, V> first, e;
          int n;
          K k;
          if ((tab = table) != null
                  && (n = tab.length) > 0
                  && (first = tab[(n - 1) & hash]) != null) {
              if (first.hash == hash
                      && // always check first node
                      ((k = first.key) == key || (key != null && keyEquals(key, k)))) {
                  return first;
              }
              if ((e = first.next) != null) {
                  if (first instanceof TreeNode) {
                      return ((TreeNode<K, V>) first).getTreeNode(hash, key);
                  }
                  do {
                      if (e.hash == hash
                              && ((k = e.key) == key || (key != null && keyEquals(key, k)))) {
                          return e;
                      }
                  } while ((e = e.next) != null);
              }
          }
          return null;
      }
  
      /**
       * Returns {@code true} if this map contains a mapping for the specified key.
       *
       * @param key The key whose presence in this map is to be tested
       * @return {@code true} if this map contains a mapping for the specified key.
       */
      public boolean containsKey(Object key) {
          return getNode(hash(key), key) != null;
      }
  
      /**
       * Associates the specified value with the specified key in this map. If the map previously
       * contained a mapping for the key, the old value is replaced.
       *
       * @param key key with which the specified value is to be associated
       * @param value value to be associated with the specified key
       * @return the previous value associated with {@code key}, or {@code null} if there was no
       *     mapping for {@code key}. (A {@code null} return can also indicate that the map previously
       *     associated {@code null} with {@code key}.)
       */
      public V put(K key, V value) {
          return putVal(hash(key), key, value, false, true);
      }
  
      /**
       * Implements Map.put and related methods
       *
       * @param hash hash for key
       * @param key the key
       * @param value the value to put
       * @param onlyIfAbsent if true, don't change existing value
       * @param evict if false, the table is in creation mode.
       * @return previous value, or null if none
       */
      final V putVal(int hash, K key, V value, boolean onlyIfAbsent, boolean evict) {
          Node<K, V>[] tab;
          Node<K, V> p;
          int n, i;
          if ((tab = table) == null || (n = tab.length) == 0) {
              n = (tab = resize()).length;
          }
          if ((p = tab[i = (n - 1) & hash]) == null) {
              tab[i] = newNode(hash, key, value, null);
          } else {
              Node<K, V> e;
              K k;
              if (p.hash == hash && ((k = p.key) == key || (key != null && keyEquals(key, k)))) {
                  e = p;
              } else if (p instanceof TreeNode) {
                  e = ((TreeNode<K, V>) p).putTreeVal(this, tab, hash, key, value);
              } else {
                  for (int binCount = 0; ; ++binCount) {
                      if ((e = p.next) == null) {
                          p.next = newNode(hash, key, value, null);
                          if (binCount >= TREEIFY_THRESHOLD - 1) // -1 for 1st
                          {
                              treeifyBin(tab, hash);
                          }
                          break;
                      }
                      if (e.hash == hash
                              && ((k = e.key) == key || (key != null && keyEquals(key, k)))) {
                          break;
                      }
                      p = e;
                  }
              }
              if (e != null) { // existing mapping for key
                  V oldValue = e.value;
                  if (!onlyIfAbsent || oldValue == null) {
                      e.value = value;
                  }
                  afterNodeAccess(e);
                  return oldValue;
              }
          }
          ++modCount;
          if (++size > threshold) {
              resize();
          }
          afterNodeInsertion(evict);
          return null;
      }
  
      /**
       * Initializes or doubles table size. If null, allocates in accord with initial capacity target
       * held in field threshold. Otherwise, because we are using power-of-two expansion, the elements
       * from each bin must either stay at same index, or move with a power of two offset in the new
       * table.
       *
       * @return the table
       */
      final Node<K, V>[] resize() {
          Node<K, V>[] oldTab = table;
          int oldCap = (oldTab == null) ? 0 : oldTab.length;
          int oldThr = threshold;
          int newCap, newThr = 0;
          if (oldCap > 0) {
              if (oldCap >= MAXIMUM_CAPACITY) {
                  threshold = Integer.MAX_VALUE;
                  return oldTab;
              } else if ((newCap = oldCap << 1) < MAXIMUM_CAPACITY
                      && oldCap >= DEFAULT_INITIAL_CAPACITY) {
                  newThr = oldThr << 1; // double threshold
              }
          } else if (oldThr > 0) // initial capacity was placed in threshold
          {
              newCap = oldThr;
          } else { // zero initial threshold signifies using defaults
              newCap = DEFAULT_INITIAL_CAPACITY;
              newThr = (int) (DEFAULT_LOAD_FACTOR * DEFAULT_INITIAL_CAPACITY);
          }
          if (newThr == 0) {
              float ft = (float) newCap * loadFactor;
              newThr =
                      (newCap < MAXIMUM_CAPACITY && ft < (float) MAXIMUM_CAPACITY
                              ? (int) ft
                              : Integer.MAX_VALUE);
          }
          threshold = newThr;
          @SuppressWarnings({"unchecked"})
          Node<K, V>[] newTab = (Node<K, V>[]) new Node[newCap];
          table = newTab;
          if (oldTab != null) {
              for (int j = 0; j < oldCap; ++j) {
                  Node<K, V> e;
                  if ((e = oldTab[j]) != null) {
                      oldTab[j] = null;
                      if (e.next == null) {
                          newTab[e.hash & (newCap - 1)] = e;
                      } else if (e instanceof TreeNode) {
                          ((TreeNode<K, V>) e).split(this, newTab, j, oldCap);
                      } else { // preserve order
                          Node<K, V> loHead = null, loTail = null;
                          Node<K, V> hiHead = null, hiTail = null;
                          Node<K, V> next;
                          do {
                              next = e.next;
                              if ((e.hash & oldCap) == 0) {
                                  if (loTail == null) {
                                      loHead = e;
                                  } else {
                                      loTail.next = e;
                                  }
                                  loTail = e;
                              } else {
                                  if (hiTail == null) {
                                      hiHead = e;
                                  } else {
                                      hiTail.next = e;
                                  }
                                  hiTail = e;
                              }
                          } while ((e = next) != null);
                          if (loTail != null) {
                              loTail.next = null;
                              newTab[j] = loHead;
                          }
                          if (hiTail != null) {
                              hiTail.next = null;
                              newTab[j + oldCap] = hiHead;
                          }
                      }
                  }
              }
          }
          return newTab;
      }
  
      /**
       * Replaces all linked nodes in bin at index for given hash unless table is too small, in which
       * case resizes instead.
       */
      final void treeifyBin(Node<K, V>[] tab, int hash) {
          int n, index;
          Node<K, V> e;
          if (tab == null || (n = tab.length) < MIN_TREEIFY_CAPACITY) {
              resize();
          } else if ((e = tab[index = (n - 1) & hash]) != null) {
              TreeNode<K, V> hd = null, tl = null;
              do {
                  TreeNode<K, V> p = replacementTreeNode(e, null);
                  if (tl == null) {
                      hd = p;
                  } else {
                      p.prev = tl;
                      tl.next = p;
                  }
                  tl = p;
              } while ((e = e.next) != null);
              if ((tab[index] = hd) != null) {
                  hd.treeify(tab);
              }
          }
      }
  
      /**
       * Copies all of the mappings from the specified map to this map. These mappings will replace
       * any mappings that this map had for any of the keys currently in the specified map.
       *
       * @param m mappings to be stored in this map
       * @throws NullPointerException if the specified map is null
       */
      public void putAll(Map<? extends K, ? extends V> m) {
          putMapEntries(m, true);
      }
  
      /**
       * Removes the mapping for the specified key from this map if present.
       *
       * @param key key whose mapping is to be removed from the map
       * @return the previous value associated with {@code key}, or {@code null} if there was no
       *     mapping for {@code key}. (A {@code null} return can also indicate that the map previously
       *     associated {@code null} with {@code key}.)
       */
      public V remove(Object key) {
          Node<K, V> e;
          return (e = removeNode(hash(key), key, null, false, true)) == null ? null : e.value;
      }
  
      /**
       * Implements Map.remove and related methods
       *
       * @param hash hash for key
       * @param key the key
       * @param value the value to match if matchValue, else ignored
       * @param matchValue if true only remove if value is equal
       * @param movable if false do not move other nodes while removing
       * @return the node, or null if none
       */
      final Node<K, V> removeNode(
              int hash, Object key, Object value, boolean matchValue, boolean movable) {
          Node<K, V>[] tab;
          Node<K, V> p;
          int n, index;
          if ((tab = table) != null
                  && (n = tab.length) > 0
                  && (p = tab[index = (n - 1) & hash]) != null) {
              Node<K, V> node = null, e;
              K k;
              V v;
              if (p.hash == hash && ((k = p.key) == key || (key != null && keyEquals(key, k)))) {
                  node = p;
              } else if ((e = p.next) != null) {
                  if (p instanceof TreeNode) {
                      node = ((TreeNode<K, V>) p).getTreeNode(hash, key);
                  } else {
                      do {
                          if (e.hash == hash
                                  && ((k = e.key) == key || (key != null && keyEquals(key, k)))) {
                              node = e;
                              break;
                          }
                          p = e;
                      } while ((e = e.next) != null);
                  }
              }
              if (node != null
                      && (!matchValue
                              || (v = node.value) == value
                              || (value != null && valEquals(value, v)))) {
                  if (node instanceof TreeNode) {
                      ((TreeNode<K, V>) node).removeTreeNode(this, tab, movable);
                  } else if (node == p) {
                      tab[index] = node.next;
                  } else {
                      p.next = node.next;
                  }
                  ++modCount;
                  --size;
                  afterNodeRemoval(node);
                  return node;
              }
          }
          return null;
      }
  
      /** Removes all of the mappings from this map. The map will be empty after this call returns. */
      public void clear() {
          Node<K, V>[] tab;
          modCount++;
          if ((tab = table) != null && size > 0) {
              size = 0;
              for (int i = 0; i < tab.length; ++i) {
                  tab[i] = null;
              }
          }
      }
  
      /**
       * Returns {@code true} if this map maps one or more keys to the specified value.
       *
       * @param value value whose presence in this map is to be tested
       * @return {@code true} if this map maps one or more keys to the specified value
       */
      public boolean containsValue(Object value) {
          Node<K, V>[] tab;
          V v;
          if ((tab = table) != null && size > 0) {
              for (Node<K, V> e : tab) {
                  for (; e != null; e = e.next) {
                      if ((v = e.value) == value || (value != null && valEquals(value, v))) {
                          return true;
                      }
                  }
              }
          }
          return false;
      }
  
      /**
       * Returns a {@link Set} view of the keys contained in this map. The set is backed by the map,
       * so changes to the map are reflected in the set, and vice-versa. If the map is modified while
       * an iteration over the set is in progress (except through the iterator's own {@code remove}
       * operation), the results of the iteration are undefined. The set supports element removal,
       * which removes the corresponding mapping from the map, via the {@code Iterator.remove}, {@code
       * Set.remove}, {@code removeAll}, {@code retainAll}, and {@code clear} operations. It does not
       * support the {@code add} or {@code addAll} operations.
       *
       * @return a set view of the keys contained in this map
       */
      public Set<K> keySet() {
          Set<K> ks = keySet;
          if (ks == null) {
              ks = new KeySet();
              keySet = ks;
          }
          return ks;
      }
  
      final class KeySet extends AbstractSet<K> {
  
          public final int size() {
              return size;
          }
  
          public final void clear() {
              HashMap.this.clear();
          }
  
          public final Iterator<K> iterator() {
              return new KeyIterator();
          }
  
          public final boolean contains(Object o) {
              return containsKey(o);
          }
  
          public final boolean remove(Object key) {
              return removeNode(hash(key), key, null, false, true) != null;
          }
  
          public final Spliterator<K> spliterator() {
              return new KeySpliterator<>(HashMap.this, 0, -1, 0, 0);
          }
  
          public final void forEach(Consumer<? super K> action) {
              Node<K, V>[] tab;
              if (action == null) {
                  throw new NullPointerException();
              }
              if (size > 0 && (tab = table) != null) {
                  int mc = modCount;
                  for (Node<K, V> e : tab) {
                      for (; e != null; e = e.next) {
                          action.accept(e.key);
                      }
                  }
                  if (modCount != mc) {
                      throw new ConcurrentModificationException();
                  }
              }
          }
      }
  
      /**
       * Returns a {@link Collection} view of the values contained in this map. The collection is
       * backed by the map, so changes to the map are reflected in the collection, and vice-versa. If
       * the map is modified while an iteration over the collection is in progress (except through the
       * iterator's own {@code remove} operation), the results of the iteration are undefined. The
       * collection supports element removal, which removes the corresponding mapping from the map,
       * via the {@code Iterator.remove}, {@code Collection.remove}, {@code removeAll}, {@code
       * retainAll} and {@code clear} operations. It does not support the {@code add} or {@code
       * addAll} operations.
       *
       * @return a view of the values contained in this map
       */
      public Collection<V> values() {
          Collection<V> vs = values;
          if (vs == null) {
              vs = new Values();
              values = vs;
          }
          return vs;
      }
  
      final class Values extends AbstractCollection<V> {
  
          public final int size() {
              return size;
          }
  
          public final void clear() {
              HashMap.this.clear();
          }
  
          public final Iterator<V> iterator() {
              return new ValueIterator();
          }
  
          public final boolean contains(Object o) {
              return containsValue(o);
          }
  
          public final Spliterator<V> spliterator() {
              return new ValueSpliterator<>(HashMap.this, 0, -1, 0, 0);
          }
  
          public final void forEach(Consumer<? super V> action) {
              Node<K, V>[] tab;
              if (action == null) {
                  throw new NullPointerException();
              }
              if (size > 0 && (tab = table) != null) {
                  int mc = modCount;
                  for (Node<K, V> e : tab) {
                      for (; e != null; e = e.next) {
                          action.accept(e.value);
                      }
                  }
                  if (modCount != mc) {
                      throw new ConcurrentModificationException();
                  }
              }
          }
      }
  
      /**
       * Returns a {@link Set} view of the mappings contained in this map. The set is backed by the
       * map, so changes to the map are reflected in the set, and vice-versa. If the map is modified
       * while an iteration over the set is in progress (except through the iterator's own {@code
       * remove} operation, or through the {@code setValue} operation on a map entry returned by the
       * iterator) the results of the iteration are undefined. The set supports element removal, which
       * removes the corresponding mapping from the map, via the {@code Iterator.remove}, {@code
       * Set.remove}, {@code removeAll}, {@code retainAll} and {@code clear} operations. It does not
       * support the {@code add} or {@code addAll} operations.
       *
       * @return a set view of the mappings contained in this map
       */
      public Set<Map.Entry<K, V>> entrySet() {
          Set<Map.Entry<K, V>> es;
          return (es = entrySet) == null ? (entrySet = new EntrySet()) : es;
      }
  
      final class EntrySet extends AbstractSet<Map.Entry<K, V>> {
  
          public final int size() {
              return size;
          }
  
          public final void clear() {
              HashMap.this.clear();
          }
  
          public final Iterator<Map.Entry<K, V>> iterator() {
              return new EntryIterator();
          }
  
          public final boolean contains(Object o) {
              if (!(o instanceof Map.Entry)) {
                  return false;
              }
              Map.Entry<?, ?> e = (Map.Entry<?, ?>) o;
              Object key = e.getKey();
              Node<K, V> candidate = getNode(hash(key), key);
              return candidate != null && candidate.equals(e);
          }
  
          public final boolean remove(Object o) {
              if (o instanceof Map.Entry) {
                  Map.Entry<?, ?> e = (Map.Entry<?, ?>) o;
                  Object key = e.getKey();
                  Object value = e.getValue();
                  return removeNode(hash(key), key, value, true, true) != null;
              }
              return false;
          }
  
          public final Spliterator<Map.Entry<K, V>> spliterator() {
              return new EntrySpliterator<>(HashMap.this, 0, -1, 0, 0);
          }
  
          public final void forEach(Consumer<? super Map.Entry<K, V>> action) {
              Node<K, V>[] tab;
              if (action == null) {
                  throw new NullPointerException();
              }
              if (size > 0 && (tab = table) != null) {
                  int mc = modCount;
                  for (Node<K, V> e : tab) {
                      for (; e != null; e = e.next) {
                          action.accept(e);
                      }
                  }
                  if (modCount != mc) {
                      throw new ConcurrentModificationException();
                  }
              }
          }
      }
  
      // Overrides of JDK8 Map extension methods
      @Override
      public V getOrDefault(Object key, V defaultValue) {
          Node<K, V> e;
          return (e = getNode(hash(key), key)) == null ? defaultValue : e.value;
      }
  
      @Override
      public V putIfAbsent(K key, V value) {
          return putVal(hash(key), key, value, true, true);
      }
  
      @Override
      public boolean remove(Object key, Object value) {
          return removeNode(hash(key), key, value, true, true) != null;
      }
  
      @Override
      public boolean replace(K key, V oldValue, V newValue) {
          Node<K, V> e;
          V v;
          if ((e = getNode(hash(key), key)) != null
                  && ((v = e.value) == oldValue || (v != null && valEquals(oldValue, v)))) {
              e.value = newValue;
              afterNodeAccess(e);
              return true;
          }
          return false;
      }
  
      @Override
      public V replace(K key, V value) {
          Node<K, V> e;
          if ((e = getNode(hash(key), key)) != null) {
              V oldValue = e.value;
              e.value = value;
              afterNodeAccess(e);
              return oldValue;
          }
          return null;
      }
  
      /**
       * {@inheritDoc}
       *
       * <p>This method will, on a best-effort basis, throw a {@link ConcurrentModificationException}
       * if it is detected that the mapping function modifies this map during computation.
       *
       * @throws ConcurrentModificationException if it is detected that the mapping function modified
       *     this map
       */
      @Override
      public V computeIfAbsent(K key, Function<? super K, ? extends V> mappingFunction) {
          if (mappingFunction == null) {
              throw new NullPointerException();
          }
          int hash = hash(key);
          Node<K, V>[] tab;
          Node<K, V> first;
          int n, i;
          int binCount = 0;
          TreeNode<K, V> t = null;
          Node<K, V> old = null;
          if (size > threshold || (tab = table) == null || (n = tab.length) == 0) {
              n = (tab = resize()).length;
          }
          if ((first = tab[i = (n - 1) & hash]) != null) {
              if (first instanceof TreeNode) {
                  old = (t = (TreeNode<K, V>) first).getTreeNode(hash, key);
              } else {
                  Node<K, V> e = first;
                  K k;
                  do {
                      if (e.hash == hash
                              && ((k = e.key) == key || (key != null && keyEquals(key, k)))) {
                          old = e;
                          break;
                      }
                      ++binCount;
                  } while ((e = e.next) != null);
              }
              V oldValue;
              if (old != null && (oldValue = old.value) != null) {
                  afterNodeAccess(old);
                  return oldValue;
              }
          }
          int mc = modCount;
          V v = mappingFunction.apply(key);
          if (mc != modCount) {
              throw new ConcurrentModificationException();
          }
          if (v == null) {
              return null;
          } else if (old != null) {
              old.value = v;
              afterNodeAccess(old);
              return v;
          } else if (t != null) {
              t.putTreeVal(this, tab, hash, key, v);
          } else {
              tab[i] = newNode(hash, key, v, first);
              if (binCount >= TREEIFY_THRESHOLD - 1) {
                  treeifyBin(tab, hash);
              }
          }
          modCount = mc + 1;
          ++size;
          afterNodeInsertion(true);
          return v;
      }
  
      /**
       * {@inheritDoc}
       *
       * <p>This method will, on a best-effort basis, throw a {@link ConcurrentModificationException}
       * if it is detected that the remapping function modifies this map during computation.
       *
       * @throws ConcurrentModificationException if it is detected that the remapping function
       *     modified this map
       */
      @Override
      public V computeIfPresent(
              K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
          if (remappingFunction == null) {
              throw new NullPointerException();
          }
          Node<K, V> e;
          V oldValue;
          int hash = hash(key);
          if ((e = getNode(hash, key)) != null && (oldValue = e.value) != null) {
              int mc = modCount;
              V v = remappingFunction.apply(key, oldValue);
              if (mc != modCount) {
                  throw new ConcurrentModificationException();
              }
              if (v != null) {
                  e.value = v;
                  afterNodeAccess(e);
                  return v;
              } else {
                  removeNode(hash, key, null, false, true);
              }
          }
          return null;
      }
  
      /**
       * {@inheritDoc}
       *
       * <p>This method will, on a best-effort basis, throw a {@link ConcurrentModificationException}
       * if it is detected that the remapping function modifies this map during computation.
       *
       * @throws ConcurrentModificationException if it is detected that the remapping function
       *     modified this map
       */
      @Override
      public V compute(K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
          if (remappingFunction == null) {
              throw new NullPointerException();
          }
          int hash = hash(key);
          Node<K, V>[] tab;
          Node<K, V> first;
          int n, i;
          int binCount = 0;
          TreeNode<K, V> t = null;
          Node<K, V> old = null;
          if (size > threshold || (tab = table) == null || (n = tab.length) == 0) {
              n = (tab = resize()).length;
          }
          if ((first = tab[i = (n - 1) & hash]) != null) {
              if (first instanceof TreeNode) {
                  old = (t = (TreeNode<K, V>) first).getTreeNode(hash, key);
              } else {
                  Node<K, V> e = first;
                  K k;
                  do {
                      if (e.hash == hash
                              && ((k = e.key) == key || (key != null && keyEquals(key, k)))) {
                          old = e;
                          break;
                      }
                      ++binCount;
                  } while ((e = e.next) != null);
              }
          }
          V oldValue = (old == null) ? null : old.value;
          int mc = modCount;
          V v = remappingFunction.apply(key, oldValue);
          if (mc != modCount) {
              throw new ConcurrentModificationException();
          }
          if (old != null) {
              if (v != null) {
                  old.value = v;
                  afterNodeAccess(old);
              } else {
                  removeNode(hash, key, null, false, true);
              }
          } else if (v != null) {
              if (t != null) {
                  t.putTreeVal(this, tab, hash, key, v);
              } else {
                  tab[i] = newNode(hash, key, v, first);
                  if (binCount >= TREEIFY_THRESHOLD - 1) {
                      treeifyBin(tab, hash);
                  }
              }
              modCount = mc + 1;
              ++size;
              afterNodeInsertion(true);
          }
          return v;
      }
  
      /**
       * {@inheritDoc}
       *
       * <p>This method will, on a best-effort basis, throw a {@link ConcurrentModificationException}
       * if it is detected that the remapping function modifies this map during computation.
       *
       * @throws ConcurrentModificationException if it is detected that the remapping function
       *     modified this map
       */
      @Override
      public V merge(
              K key, V value, BiFunction<? super V, ? super V, ? extends V> remappingFunction) {
          if (value == null) {
              throw new NullPointerException();
          }
          if (remappingFunction == null) {
              throw new NullPointerException();
          }
          int hash = hash(key);
          Node<K, V>[] tab;
          Node<K, V> first;
          int n, i;
          int binCount = 0;
          TreeNode<K, V> t = null;
          Node<K, V> old = null;
          if (size > threshold || (tab = table) == null || (n = tab.length) == 0) {
              n = (tab = resize()).length;
          }
          if ((first = tab[i = (n - 1) & hash]) != null) {
              if (first instanceof TreeNode) {
                  old = (t = (TreeNode<K, V>) first).getTreeNode(hash, key);
              } else {
                  Node<K, V> e = first;
                  K k;
                  do {
                      if (e.hash == hash
                              && ((k = e.key) == key || (key != null && keyEquals(key, k)))) {
                          old = e;
                          break;
                      }
                      ++binCount;
                  } while ((e = e.next) != null);
              }
          }
          if (old != null) {
              V v;
              if (old.value != null) {
                  int mc = modCount;
                  v = remappingFunction.apply(old.value, value);
                  if (mc != modCount) {
                      throw new ConcurrentModificationException();
                  }
              } else {
                  v = value;
              }
              if (v != null) {
                  old.value = v;
                  afterNodeAccess(old);
              } else {
                  removeNode(hash, key, null, false, true);
              }
              return v;
          }
          if (value != null) {
              if (t != null) {
                  t.putTreeVal(this, tab, hash, key, value);
              } else {
                  tab[i] = newNode(hash, key, value, first);
                  if (binCount >= TREEIFY_THRESHOLD - 1) {
                      treeifyBin(tab, hash);
                  }
              }
              ++modCount;
              ++size;
              afterNodeInsertion(true);
          }
          return value;
      }
  
      @Override
      public void forEach(BiConsumer<? super K, ? super V> action) {
          Node<K, V>[] tab;
          if (action == null) {
              throw new NullPointerException();
          }
          if (size > 0 && (tab = table) != null) {
              int mc = modCount;
              for (Node<K, V> e : tab) {
                  for (; e != null; e = e.next) {
                      action.accept(e.key, e.value);
                  }
              }
              if (modCount != mc) {
                  throw new ConcurrentModificationException();
              }
          }
      }
  
      @Override
      public void replaceAll(BiFunction<? super K, ? super V, ? extends V> function) {
          Node<K, V>[] tab;
          if (function == null) {
              throw new NullPointerException();
          }
          if (size > 0 && (tab = table) != null) {
              int mc = modCount;
              for (Node<K, V> e : tab) {
                  for (; e != null; e = e.next) {
                      e.value = function.apply(e.key, e.value);
                  }
              }
              if (modCount != mc) {
                  throw new ConcurrentModificationException();
              }
          }
      }
  
      /* ------------------------------------------------------------ */
      // Cloning and serialization
      /**
       * Returns a shallow copy of this {@code HashMap} instance: the keys and values themselves are
       * not cloned.
       *
       * @return a shallow copy of this map
       */
      @SuppressWarnings("unchecked")
      @Override
      public Object clone() {
          HashMap<K, V> result;
          try {
              result = (HashMap<K, V>) super.clone();
          } catch (CloneNotSupportedException e) {
              // this shouldn't happen, since we are Cloneable
              throw new InternalError(e);
          }
          result.reinitialize();
          result.putMapEntries(this, false);
          return result;
      }
  
      // These methods are also used when serializing HashSets
      final float loadFactor() {
          return loadFactor;
      }
  
      final int capacity() {
          return (table != null)
                  ? table.length
                  : (threshold > 0) ? threshold : DEFAULT_INITIAL_CAPACITY;
      }
  
      /**
       * Save the state of the {@code HashMap} instance to a stream (i.e., serialize it).
       *
       * @serialData The <i>capacity</i> of the HashMap (the length of the bucket array) is emitted
       *     (int), followed by the <i>size</i> (an int, the number of key-value mappings), followed
       *     by the key (Object) and value (Object) for each key-value mapping. The key-value mappings
       *     are emitted in no particular order.
       */
      private void writeObject(java.io.ObjectOutputStream s) throws IOException {
          int buckets = capacity();
          // Write out the threshold, loadfactor, and any hidden stuff
          s.defaultWriteObject();
          s.writeInt(buckets);
          s.writeInt(size);
          internalWriteEntries(s);
      }
  
      /** Reconstitute the {@code HashMap} instance from a stream (i.e., deserialize it). */
      private void readObject(java.io.ObjectInputStream s)
              throws IOException, ClassNotFoundException {
          // Read in the threshold (ignored), loadfactor, and any hidden stuff
          s.defaultReadObject();
          reinitialize();
          if (loadFactor <= 0 || Float.isNaN(loadFactor)) {
              throw new InvalidObjectException("Illegal load factor: " + loadFactor);
          }
          s.readInt(); // Read and ignore number of buckets
          int mappings = s.readInt(); // Read number of mappings (size)
          if (mappings < 0) {
              throw new InvalidObjectException("Illegal mappings count: " + mappings);
          } else if (mappings > 0) { // (if zero, use defaults)
              // Size the table using given load factor only if within
              // range of 0.25...4.0
              float lf = Math.min(Math.max(0.25f, loadFactor), 4.0f);
              float fc = (float) mappings / lf + 1.0f;
              int cap =
                      ((fc < DEFAULT_INITIAL_CAPACITY)
                              ? DEFAULT_INITIAL_CAPACITY
                              : (fc >= MAXIMUM_CAPACITY) ? MAXIMUM_CAPACITY : tableSizeFor((int) fc));
              float ft = (float) cap * lf;
              threshold =
                      ((cap < MAXIMUM_CAPACITY && ft < MAXIMUM_CAPACITY)
                              ? (int) ft
                              : Integer.MAX_VALUE);
              @SuppressWarnings({"unchecked"})
              Node<K, V>[] tab = (Node<K, V>[]) new Node[cap];
              table = tab;
  
              // Read the keys and values, and put the mappings in the HashMap
              for (int i = 0; i < mappings; i++) {
                  @SuppressWarnings("unchecked")
                  K key = (K) s.readObject();
                  @SuppressWarnings("unchecked")
                  V value = (V) s.readObject();
                  putVal(hash(key), key, value, false, false);
              }
          }
      }
  
      /* ------------------------------------------------------------ */
      // iterators
      abstract class HashIterator {
  
          Node<K, V> next; // next entry to return
          Node<K, V> current; // current entry
          int expectedModCount; // for fast-fail
          int index; // current slot
  
          HashIterator() {
              expectedModCount = modCount;
              Node<K, V>[] t = table;
              current = next = null;
              index = 0;
              if (t != null && size > 0) { // advance to first entry
                  do {} while (index < t.length && (next = t[index++]) == null);
              }
          }
  
          public final boolean hasNext() {
              return next != null;
          }
  
          final Node<K, V> nextNode() {
              Node<K, V>[] t;
              Node<K, V> e = next;
              if (modCount != expectedModCount) {
                  throw new ConcurrentModificationException();
              }
              if (e == null) {
                  throw new NoSuchElementException();
              }
              if ((next = (current = e).next) == null && (t = table) != null) {
                  do {} while (index < t.length && (next = t[index++]) == null);
              }
              return e;
          }
  
          public final void remove() {
              Node<K, V> p = current;
              if (p == null) {
                  throw new IllegalStateException();
              }
              if (modCount != expectedModCount) {
                  throw new ConcurrentModificationException();
              }
              current = null;
              K key = p.key;
              removeNode(hash(key), key, null, false, false);
              expectedModCount = modCount;
          }
      }
  
      final class KeyIterator extends HashIterator implements Iterator<K> {
  
          public final K next() {
              return nextNode().key;
          }
      }
  
      final class ValueIterator extends HashIterator implements Iterator<V> {
  
          public final V next() {
              return nextNode().value;
          }
      }
  
      final class EntryIterator extends HashIterator implements Iterator<Map.Entry<K, V>> {
  
          public final Map.Entry<K, V> next() {
              return nextNode();
          }
      }
  
      /* ------------------------------------------------------------ */
      // spliterators
      static class HashMapSpliterator<K, V> {
  
          final HashMap<K, V> map;
          Node<K, V> current; // current node
          int index; // current index, modified on advance/split
          int fence; // one past last index
          int est; // size estimate
          int expectedModCount; // for comodification checks
  
          HashMapSpliterator(HashMap<K, V> m, int origin, int fence, int est, int expectedModCount) {
              this.map = m;
              this.index = origin;
              this.fence = fence;
              this.est = est;
              this.expectedModCount = expectedModCount;
          }
  
          final int getFence() { // initialize fence and size on first use
              int hi;
              if ((hi = fence) < 0) {
                  HashMap<K, V> m = map;
                  est = m.size;
                  expectedModCount = m.modCount;
                  Node<K, V>[] tab = m.table;
                  hi = fence = (tab == null) ? 0 : tab.length;
              }
              return hi;
          }
  
          public final long estimateSize() {
              getFence(); // force init
              return (long) est;
          }
      }
  
      static final class KeySpliterator<K, V> extends HashMapSpliterator<K, V>
              implements Spliterator<K> {
  
          KeySpliterator(HashMap<K, V> m, int origin, int fence, int est, int expectedModCount) {
              super(m, origin, fence, est, expectedModCount);
          }
  
          public KeySpliterator<K, V> trySplit() {
              int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
              return (lo >= mid || current != null)
                      ? null
                      : new KeySpliterator<>(map, lo, index = mid, est >>>= 1, expectedModCount);
          }
  
          public void forEachRemaining(Consumer<? super K> action) {
              int i, hi, mc;
              if (action == null) {
                  throw new NullPointerException();
              }
              HashMap<K, V> m = map;
              Node<K, V>[] tab = m.table;
              if ((hi = fence) < 0) {
                  mc = expectedModCount = m.modCount;
                  hi = fence = (tab == null) ? 0 : tab.length;
              } else {
                  mc = expectedModCount;
              }
              if (tab != null
                      && tab.length >= hi
                      && (i = index) >= 0
                      && (i < (index = hi) || current != null)) {
                  Node<K, V> p = current;
                  current = null;
                  do {
                      if (p == null) {
                          p = tab[i++];
                      } else {
                          action.accept(p.key);
                          p = p.next;
                      }
                  } while (p != null || i < hi);
                  if (m.modCount != mc) {
                      throw new ConcurrentModificationException();
                  }
              }
          }
  
          public boolean tryAdvance(Consumer<? super K> action) {
              int hi;
              if (action == null) {
                  throw new NullPointerException();
              }
              Node<K, V>[] tab = map.table;
              if (tab != null && tab.length >= (hi = getFence()) && index >= 0) {
                  while (current != null || index < hi) {
                      if (current == null) {
                          current = tab[index++];
                      } else {
                          K k = current.key;
                          current = current.next;
                          action.accept(k);
                          if (map.modCount != expectedModCount) {
                              throw new ConcurrentModificationException();
                          }
                          return true;
                      }
                  }
              }
              return false;
          }
  
          public int characteristics() {
              return (fence < 0 || est == map.size ? Spliterator.SIZED : 0) | Spliterator.DISTINCT;
          }
      }
  
      static final class ValueSpliterator<K, V> extends HashMapSpliterator<K, V>
              implements Spliterator<V> {
  
          ValueSpliterator(HashMap<K, V> m, int origin, int fence, int est, int expectedModCount) {
              super(m, origin, fence, est, expectedModCount);
          }
  
          public ValueSpliterator<K, V> trySplit() {
              int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
              return (lo >= mid || current != null)
                      ? null
                      : new ValueSpliterator<>(map, lo, index = mid, est >>>= 1, expectedModCount);
          }
  
          public void forEachRemaining(Consumer<? super V> action) {
              int i, hi, mc;
              if (action == null) {
                  throw new NullPointerException();
              }
              HashMap<K, V> m = map;
              Node<K, V>[] tab = m.table;
              if ((hi = fence) < 0) {
                  mc = expectedModCount = m.modCount;
                  hi = fence = (tab == null) ? 0 : tab.length;
              } else {
                  mc = expectedModCount;
              }
              if (tab != null
                      && tab.length >= hi
                      && (i = index) >= 0
                      && (i < (index = hi) || current != null)) {
                  Node<K, V> p = current;
                  current = null;
                  do {
                      if (p == null) {
                          p = tab[i++];
                      } else {
                          action.accept(p.value);
                          p = p.next;
                      }
                  } while (p != null || i < hi);
                  if (m.modCount != mc) {
                      throw new ConcurrentModificationException();
                  }
              }
          }
  
          public boolean tryAdvance(Consumer<? super V> action) {
              int hi;
              if (action == null) {
                  throw new NullPointerException();
              }
              Node<K, V>[] tab = map.table;
              if (tab != null && tab.length >= (hi = getFence()) && index >= 0) {
                  while (current != null || index < hi) {
                      if (current == null) {
                          current = tab[index++];
                      } else {
                          V v = current.value;
                          current = current.next;
                          action.accept(v);
                          if (map.modCount != expectedModCount) {
                              throw new ConcurrentModificationException();
                          }
                          return true;
                      }
                  }
              }
              return false;
          }
  
          public int characteristics() {
              return (fence < 0 || est == map.size ? Spliterator.SIZED : 0);
          }
      }
  
      static final class EntrySpliterator<K, V> extends HashMapSpliterator<K, V>
              implements Spliterator<Map.Entry<K, V>> {
  
          EntrySpliterator(HashMap<K, V> m, int origin, int fence, int est, int expectedModCount) {
              super(m, origin, fence, est, expectedModCount);
          }
  
          public EntrySpliterator<K, V> trySplit() {
              int hi = getFence(), lo = index, mid = (lo + hi) >>> 1;
              return (lo >= mid || current != null)
                      ? null
                      : new EntrySpliterator<>(map, lo, index = mid, est >>>= 1, expectedModCount);
          }
  
          public void forEachRemaining(Consumer<? super Map.Entry<K, V>> action) {
              int i, hi, mc;
              if (action == null) {
                  throw new NullPointerException();
              }
              HashMap<K, V> m = map;
              Node<K, V>[] tab = m.table;
              if ((hi = fence) < 0) {
                  mc = expectedModCount = m.modCount;
                  hi = fence = (tab == null) ? 0 : tab.length;
              } else {
                  mc = expectedModCount;
              }
              if (tab != null
                      && tab.length >= hi
                      && (i = index) >= 0
                      && (i < (index = hi) || current != null)) {
                  Node<K, V> p = current;
                  current = null;
                  do {
                      if (p == null) {
                          p = tab[i++];
                      } else {
                          action.accept(p);
                          p = p.next;
                      }
                  } while (p != null || i < hi);
                  if (m.modCount != mc) {
                      throw new ConcurrentModificationException();
                  }
              }
          }
  
          public boolean tryAdvance(Consumer<? super Map.Entry<K, V>> action) {
              int hi;
              if (action == null) {
                  throw new NullPointerException();
              }
              Node<K, V>[] tab = map.table;
              if (tab != null && tab.length >= (hi = getFence()) && index >= 0) {
                  while (current != null || index < hi) {
                      if (current == null) {
                          current = tab[index++];
                      } else {
                          Node<K, V> e = current;
                          current = current.next;
                          action.accept(e);
                          if (map.modCount != expectedModCount) {
                              throw new ConcurrentModificationException();
                          }
                          return true;
                      }
                  }
              }
              return false;
          }
  
          public int characteristics() {
              return (fence < 0 || est == map.size ? Spliterator.SIZED : 0) | Spliterator.DISTINCT;
          }
      }
  
      /* ------------------------------------------------------------ */
      // LinkedHashMap support
      /*
       * The following package-protected methods are designed to be
       * overridden by LinkedHashMap, but not by any other subclass.
       * Nearly all other internal methods are also package-protected
       * but are declared final, so can be used by LinkedHashMap, view
       * classes, and HashSet.
       */
      protected abstract Node<K, V> newNode(int hash, K key, V value, Node<K, V> next);
  
      // For conversion from TreeNodes to plain nodes
      protected abstract Node<K, V> replacementNode(Node<K, V> p, Node<K, V> next);
  
      // Create a tree bin node
      protected abstract TreeNode<K, V> newTreeNode(int hash, K key, V value, Node<K, V> next);
      // {
      //        return new TreeNode<>(hash, key, value, next);
      //    }
  
      // For treeifyBin
      protected abstract TreeNode<K, V> replacementTreeNode(Node<K, V> p, Node<K, V> next);
      // {
      //        return new TreeNode<>(p.hash, p.key, p.value, next);
      //    }
  
      /** Reset to initial default state. Called by clone and readObject. */
      void reinitialize() {
          table = null;
          entrySet = null;
          keySet = null;
          values = null;
          modCount = 0;
          threshold = 0;
          size = 0;
      }
  
      // Callbacks to allow LinkedHashMap post-actions
      void afterNodeAccess(Node<K, V> p) {}
  
      void afterNodeInsertion(boolean evict) {}
  
      void afterNodeRemoval(Node<K, V> p) {}
  
      // Called only from writeObject, to ensure compatible ordering.
      void internalWriteEntries(java.io.ObjectOutputStream s) throws IOException {
          Node<K, V>[] tab;
          if (size > 0 && (tab = table) != null) {
              for (Node<K, V> e : tab) {
                  for (; e != null; e = e.next) {
                      s.writeObject(e.key);
                      s.writeObject(e.value);
                  }
              }
          }
      }
  
      /* ------------------------------------------------------------ */
      // Tree bins
      /**
       * Entry for Tree bins. Extends Entry (which in turn extends Node) so can be used as extension
       * of either regular or linked node.
       */
      abstract static class TreeNode<K, V> extends Entry<K, V> {
  
          protected abstract boolean keyEquals(Object key, K k);
  
          protected abstract boolean valEquals(Object value, V v);
  
          TreeNode<K, V> parent; // red-black tree links
          TreeNode<K, V> left;
          TreeNode<K, V> right;
          TreeNode<K, V> prev; // needed to unlink next upon deletion
          boolean red;
  
          TreeNode(int hash, K key, V val, Node<K, V> next) {
              super(hash, key, val, next);
          }
  
          /** Returns root of tree containing this node. */
          final TreeNode<K, V> root() {
              for (TreeNode<K, V> r = this, p; ; ) {
                  if ((p = r.parent) == null) {
                      return r;
                  }
                  r = p;
              }
          }
  
          /** Ensures that the given root is the first node of its bin. */
          static <K, V> void moveRootToFront(Node<K, V>[] tab, TreeNode<K, V> root) {
              int n;
              if (root != null && tab != null && (n = tab.length) > 0) {
                  int index = (n - 1) & root.hash;
                  TreeNode<K, V> first = (TreeNode<K, V>) tab[index];
                  if (root != first) {
                      Node<K, V> rn;
                      tab[index] = root;
                      TreeNode<K, V> rp = root.prev;
                      if ((rn = root.next) != null) {
                          ((TreeNode<K, V>) rn).prev = rp;
                      }
                      if (rp != null) {
                          rp.next = rn;
                      }
                      if (first != null) {
                          first.prev = root;
                      }
                      root.next = first;
                      root.prev = null;
                  }
                  assert checkInvariants(root);
              }
          }
  
          /**
           * Finds the node starting at root p with the given hash and key. The kc argument caches
           * comparableClassFor(key) upon first use comparing keys.
           */
          final TreeNode<K, V> find(int h, Object k, Class<?> kc) {
              TreeNode<K, V> p = this;
              do {
                  int ph, dir;
                  K pk;
                  TreeNode<K, V> pl = p.left, pr = p.right, q;
                  if ((ph = p.hash) > h) {
                      p = pl;
                  } else if (ph < h) {
                      p = pr;
                  } else if ((pk = p.key) == k || (k != null && keyEquals(k, pk))) {
                      return p;
                  } else if (pl == null) {
                      p = pr;
                  } else if (pr == null) {
                      p = pl;
                  } else if ((kc != null || (kc = comparableClassFor(k)) != null)
                          && (dir = compareComparables(kc, k, pk)) != 0) {
                      p = (dir < 0) ? pl : pr;
                  } else if ((q = pr.find(h, k, kc)) != null) {
                      return q;
                  } else {
                      p = pl;
                  }
              } while (p != null);
              return null;
          }
  
          /** Calls find for root node. */
          final TreeNode<K, V> getTreeNode(int h, Object k) {
              return ((parent != null) ? root() : this).find(h, k, null);
          }
  
          /**
           * Tie-breaking utility for ordering insertions when equal hashCodes and non-comparable. We
           * don't require a total order, just a consistent insertion rule to maintain equivalence
           * across rebalancings. Tie-breaking further than necessary simplifies testing a bit.
           */
          static int tieBreakOrder(Object a, Object b) {
              int d;
              if (a == null
                      || b == null
                      || (d = a.getClass().getName().compareTo(b.getClass().getName())) == 0) {
                  d = (System.identityHashCode(a) <= System.identityHashCode(b) ? -1 : 1);
              }
              return d;
          }
  
          /**
           * Forms tree of the nodes linked from this node.
           *
           * @return root of tree
           */
          final void treeify(Node<K, V>[] tab) {
              TreeNode<K, V> root = null;
              for (TreeNode<K, V> x = this, next; x != null; x = next) {
                  next = (TreeNode<K, V>) x.next;
                  x.left = x.right = null;
                  if (root == null) {
                      x.parent = null;
                      x.red = false;
                      root = x;
                  } else {
                      K k = x.key;
                      int h = x.hash;
                      Class<?> kc = null;
                      for (TreeNode<K, V> p = root; ; ) {
                          int dir, ph;
                          K pk = p.key;
                          if ((ph = p.hash) > h) {
                              dir = -1;
                          } else if (ph < h) {
                              dir = 1;
                          } else if ((kc == null && (kc = comparableClassFor(k)) == null)
                                  || (dir = compareComparables(kc, k, pk)) == 0) {
                              dir = tieBreakOrder(k, pk);
                          }
  
                          TreeNode<K, V> xp = p;
                          if ((p = (dir <= 0) ? p.left : p.right) == null) {
                              x.parent = xp;
                              if (dir <= 0) {
                                  xp.left = x;
                              } else {
                                  xp.right = x;
                              }
                              root = balanceInsertion(root, x);
                              break;
                          }
                      }
                  }
              }
              moveRootToFront(tab, root);
          }
  
          /** Returns a list of non-TreeNodes replacing those linked from this node. */
          final Node<K, V> untreeify(HashMap<K, V> map) {
              Node<K, V> hd = null, tl = null;
              for (Node<K, V> q = this; q != null; q = q.next) {
                  Node<K, V> p = map.replacementNode(q, null);
                  if (tl == null) {
                      hd = p;
                  } else {
                      tl.next = p;
                  }
                  tl = p;
              }
              return hd;
          }
  
          /** Tree version of putVal. */
          final TreeNode<K, V> putTreeVal(HashMap<K, V> map, Node<K, V>[] tab, int h, K k, V v) {
              Class<?> kc = null;
              boolean searched = false;
              TreeNode<K, V> root = (parent != null) ? root() : this;
              for (TreeNode<K, V> p = root; ; ) {
                  int dir, ph;
                  K pk;
                  if ((ph = p.hash) > h) {
                      dir = -1;
                  } else if (ph < h) {
                      dir = 1;
                  } else if ((pk = p.key) == k || (k != null && keyEquals(k, pk))) {
                      return p;
                  } else if ((kc == null && (kc = comparableClassFor(k)) == null)
                          || (dir = compareComparables(kc, k, pk)) == 0) {
                      if (!searched) {
                          TreeNode<K, V> q, ch;
                          searched = true;
                          if (((ch = p.left) != null && (q = ch.find(h, k, kc)) != null)
                                  || ((ch = p.right) != null && (q = ch.find(h, k, kc)) != null)) {
                              return q;
                          }
                      }
                      dir = tieBreakOrder(k, pk);
                  }
  
                  TreeNode<K, V> xp = p;
                  if ((p = (dir <= 0) ? p.left : p.right) == null) {
                      Node<K, V> xpn = xp.next;
                      TreeNode<K, V> x = map.newTreeNode(h, k, v, xpn);
                      if (dir <= 0) {
                          xp.left = x;
                      } else {
                          xp.right = x;
                      }
                      xp.next = x;
                      x.parent = x.prev = xp;
                      if (xpn != null) {
                          ((TreeNode<K, V>) xpn).prev = x;
                      }
                      moveRootToFront(tab, balanceInsertion(root, x));
                      return null;
                  }
              }
          }
  
          /**
           * Removes the given node, that must be present before this call. This is messier than
           * typical red-black deletion code because we cannot swap the contents of an interior node
           * with a leaf successor that is pinned by "next" pointers that are accessible independently
           * during traversal. So instead we swap the tree linkages. If the current tree appears to
           * have too few nodes, the bin is converted back to a plain bin. (The test triggers
           * somewhere between 2 and 6 nodes, depending on tree structure).
           */
          final void removeTreeNode(HashMap<K, V> map, Node<K, V>[] tab, boolean movable) {
              int n;
              if (tab == null || (n = tab.length) == 0) {
                  return;
              }
              int index = (n - 1) & hash;
              TreeNode<K, V> first = (TreeNode<K, V>) tab[index], root = first, rl;
              TreeNode<K, V> succ = (TreeNode<K, V>) next, pred = prev;
              if (pred == null) {
                  tab[index] = first = succ;
              } else {
                  pred.next = succ;
              }
              if (succ != null) {
                  succ.prev = pred;
              }
              if (first == null) {
                  return;
              }
              if (root.parent != null) {
                  root = root.root();
              }
              if (root == null || root.right == null || (rl = root.left) == null || rl.left == null) {
                  tab[index] = first.untreeify(map); // too small
                  return;
              }
              TreeNode<K, V> p = this, pl = left, pr = right, replacement;
              if (pl != null && pr != null) {
                  TreeNode<K, V> s = pr, sl;
                  while ((sl = s.left) != null) // find successor
                  {
                      s = sl;
                  }
                  boolean c = s.red;
                  s.red = p.red;
                  p.red = c; // swap colors
                  TreeNode<K, V> sr = s.right;
                  TreeNode<K, V> pp = p.parent;
                  if (s == pr) { // p was s's direct parent
                      p.parent = s;
                      s.right = p;
                  } else {
                      TreeNode<K, V> sp = s.parent;
                      if ((p.parent = sp) != null) {
                          if (s == sp.left) {
                              sp.left = p;
                          } else {
                              sp.right = p;
                          }
                      }
                      if ((s.right = pr) != null) {
                          pr.parent = s;
                      }
                  }
                  p.left = null;
                  if ((p.right = sr) != null) {
                      sr.parent = p;
                  }
                  if ((s.left = pl) != null) {
                      pl.parent = s;
                  }
                  if ((s.parent = pp) == null) {
                      root = s;
                  } else if (p == pp.left) {
                      pp.left = s;
                  } else {
                      pp.right = s;
                  }
                  if (sr != null) {
                      replacement = sr;
                  } else {
                      replacement = p;
                  }
              } else if (pl != null) {
                  replacement = pl;
              } else if (pr != null) {
                  replacement = pr;
              } else {
                  replacement = p;
              }
              if (replacement != p) {
                  TreeNode<K, V> pp = replacement.parent = p.parent;
                  if (pp == null) {
                      root = replacement;
                  } else if (p == pp.left) {
                      pp.left = replacement;
                  } else {
                      pp.right = replacement;
                  }
                  p.left = p.right = p.parent = null;
              }
  
              TreeNode<K, V> r = p.red ? root : balanceDeletion(root, replacement);
  
              if (replacement == p) { // detach
                  TreeNode<K, V> pp = p.parent;
                  p.parent = null;
                  if (pp != null) {
                      if (p == pp.left) {
                          pp.left = null;
                      } else if (p == pp.right) {
                          pp.right = null;
                      }
                  }
              }
              if (movable) {
                  moveRootToFront(tab, r);
              }
          }
  
          /**
           * Splits nodes in a tree bin into lower and upper tree bins, or untreeifies if now too
           * small. Called only from resize; see above discussion about split bits and indices.
           *
           * @param map the map
           * @param tab the table for recording bin heads
           * @param index the index of the table being split
           * @param bit the bit of hash to split on
           */
          final void split(HashMap<K, V> map, Node<K, V>[] tab, int index, int bit) {
              TreeNode<K, V> b = this;
              // Relink into lo and hi lists, preserving order
              TreeNode<K, V> loHead = null, loTail = null;
              TreeNode<K, V> hiHead = null, hiTail = null;
              int lc = 0, hc = 0;
              for (TreeNode<K, V> e = b, next; e != null; e = next) {
                  next = (TreeNode<K, V>) e.next;
                  e.next = null;
                  if ((e.hash & bit) == 0) {
                      if ((e.prev = loTail) == null) {
                          loHead = e;
                      } else {
                          loTail.next = e;
                      }
                      loTail = e;
                      ++lc;
                  } else {
                      if ((e.prev = hiTail) == null) {
                          hiHead = e;
                      } else {
                          hiTail.next = e;
                      }
                      hiTail = e;
                      ++hc;
                  }
              }
  
              if (loHead != null) {
                  if (lc <= UNTREEIFY_THRESHOLD) {
                      tab[index] = loHead.untreeify(map);
                  } else {
                      tab[index] = loHead;
                      if (hiHead != null) // (else is already treeified)
                      {
                          loHead.treeify(tab);
                      }
                  }
              }
              if (hiHead != null) {
                  if (hc <= UNTREEIFY_THRESHOLD) {
                      tab[index + bit] = hiHead.untreeify(map);
                  } else {
                      tab[index + bit] = hiHead;
                      if (loHead != null) {
                          hiHead.treeify(tab);
                      }
                  }
              }
          }
  
          /* ------------------------------------------------------------ */
          // Red-black tree methods, all adapted from CLR
          static <K, V> TreeNode<K, V> rotateLeft(TreeNode<K, V> root, TreeNode<K, V> p) {
              TreeNode<K, V> r, pp, rl;
              if (p != null && (r = p.right) != null) {
                  if ((rl = p.right = r.left) != null) {
                      rl.parent = p;
                  }
                  if ((pp = r.parent = p.parent) == null) {
                      (root = r).red = false;
                  } else if (pp.left == p) {
                      pp.left = r;
                  } else {
                      pp.right = r;
                  }
                  r.left = p;
                  p.parent = r;
              }
              return root;
          }
  
          static <K, V> TreeNode<K, V> rotateRight(TreeNode<K, V> root, TreeNode<K, V> p) {
              TreeNode<K, V> l, pp, lr;
              if (p != null && (l = p.left) != null) {
                  if ((lr = p.left = l.right) != null) {
                      lr.parent = p;
                  }
                  if ((pp = l.parent = p.parent) == null) {
                      (root = l).red = false;
                  } else if (pp.right == p) {
                      pp.right = l;
                  } else {
                      pp.left = l;
                  }
                  l.right = p;
                  p.parent = l;
              }
              return root;
          }
  
          static <K, V> TreeNode<K, V> balanceInsertion(TreeNode<K, V> root, TreeNode<K, V> x) {
              x.red = true;
              for (TreeNode<K, V> xp, xpp, xppl, xppr; ; ) {
                  if ((xp = x.parent) == null) {
                      x.red = false;
                      return x;
                  } else if (!xp.red || (xpp = xp.parent) == null) {
                      return root;
                  }
                  if (xp == (xppl = xpp.left)) {
                      if ((xppr = xpp.right) != null && xppr.red) {
                          xppr.red = false;
                          xp.red = false;
                          xpp.red = true;
                          x = xpp;
                      } else {
                          if (x == xp.right) {
                              root = rotateLeft(root, x = xp);
                              xpp = (xp = x.parent) == null ? null : xp.parent;
                          }
                          if (xp != null) {
                              xp.red = false;
                              if (xpp != null) {
                                  xpp.red = true;
                                  root = rotateRight(root, xpp);
                              }
                          }
                      }
                  } else {
                      if (xppl != null && xppl.red) {
                          xppl.red = false;
                          xp.red = false;
                          xpp.red = true;
                          x = xpp;
                      } else {
                          if (x == xp.left) {
                              root = rotateRight(root, x = xp);
                              xpp = (xp = x.parent) == null ? null : xp.parent;
                          }
                          if (xp != null) {
                              xp.red = false;
                              if (xpp != null) {
                                  xpp.red = true;
                                  root = rotateLeft(root, xpp);
                              }
                          }
                      }
                  }
              }
          }
  
          static <K, V> TreeNode<K, V> balanceDeletion(TreeNode<K, V> root, TreeNode<K, V> x) {
              for (TreeNode<K, V> xp, xpl, xpr; ; ) {
                  if (x == null || x == root) {
                      return root;
                  } else if ((xp = x.parent) == null) {
                      x.red = false;
                      return x;
                  } else if (x.red) {
                      x.red = false;
                      return root;
                  } else if ((xpl = xp.left) == x) {
                      if ((xpr = xp.right) != null && xpr.red) {
                          xpr.red = false;
                          xp.red = true;
                          root = rotateLeft(root, xp);
                          xpr = (xp = x.parent) == null ? null : xp.right;
                      }
                      if (xpr == null) {
                          x = xp;
                      } else {
                          TreeNode<K, V> sl = xpr.left, sr = xpr.right;
                          if ((sr == null || !sr.red) && (sl == null || !sl.red)) {
                              xpr.red = true;
                              x = xp;
                          } else {
                              if (sr == null || !sr.red) {
                                  if (sl != null) {
                                      sl.red = false;
                                  }
                                  xpr.red = true;
                                  root = rotateRight(root, xpr);
                                  xpr = (xp = x.parent) == null ? null : xp.right;
                              }
                              if (xpr != null) {
                                  xpr.red = (xp != null) && xp.red;
                                  if ((sr = xpr.right) != null) {
                                      sr.red = false;
                                  }
                              }
                              if (xp != null) {
                                  xp.red = false;
                                  root = rotateLeft(root, xp);
                              }
                              x = root;
                          }
                      }
                  } else { // symmetric
                      if (xpl != null && xpl.red) {
                          xpl.red = false;
                          xp.red = true;
                          root = rotateRight(root, xp);
                          xpl = (xp = x.parent) == null ? null : xp.left;
                      }
                      if (xpl == null) {
                          x = xp;
                      } else {
                          TreeNode<K, V> sl = xpl.left, sr = xpl.right;
                          if ((sl == null || !sl.red) && (sr == null || !sr.red)) {
                              xpl.red = true;
                              x = xp;
                          } else {
                              if (sl == null || !sl.red) {
                                  if (sr != null) {
                                      sr.red = false;
                                  }
                                  xpl.red = true;
                                  root = rotateLeft(root, xpl);
                                  xpl = (xp = x.parent) == null ? null : xp.left;
                              }
                              if (xpl != null) {
                                  xpl.red = (xp != null) && xp.red;
                                  if ((sl = xpl.left) != null) {
                                      sl.red = false;
                                  }
                              }
                              if (xp != null) {
                                  xp.red = false;
                                  root = rotateRight(root, xp);
                              }
                              x = root;
                          }
                      }
                  }
              }
          }
  
          /** Recursive invariant check */
          static <K, V> boolean checkInvariants(TreeNode<K, V> t) {
              TreeNode<K, V> tp = t.parent,
                      tl = t.left,
                      tr = t.right,
                      tb = t.prev,
                      tn = (TreeNode<K, V>) t.next;
              if (tb != null && tb.next != t) {
                  return false;
              }
              if (tn != null && tn.prev != t) {
                  return false;
              }
              if (tp != null && t != tp.left && t != tp.right) {
                  return false;
              }
              if (tl != null && (tl.parent != t || tl.hash > t.hash)) {
                  return false;
              }
              if (tr != null && (tr.parent != t || tr.hash < t.hash)) {
                  return false;
              }
              if (t.red && tl != null && tl.red && tr != null && tr.red) {
                  return false;
              }
              if (tl != null && !checkInvariants(tl)) {
                  return false;
              }
              return tr == null || checkInvariants(tr);
          }
      }
  
      static class Entry<K, V> extends Node<K, V> {
  
          Entry<K, V> before, after;
  
          Entry(int hash, K key, V value, Node<K, V> next) {
              super(hash, key, value, next);
          }
      }
  }
  