// Unfortunately this is pasted from ImmutableCollection.Builder.
    private static int expandedCapacity(int oldCapacity, int minCapacity) {
      if (minCapacity < 0) {
        throw new AssertionError("cannot store more than MAX_VALUE elements");
      }
      // careful of overflow!
      int newCapacity = oldCapacity + (oldCapacity >> 1) + 1;
      if (newCapacity < minCapacity) {

    // Unfortunately this is pasted from ImmutableCollection.Builder.
    private static int expandedCapacity(int oldCapacity, int minCapacity) {
      if (minCapacity < 0) {
        throw new AssertionError("cannot store more than MAX_VALUE elements");
      }
      // careful of overflow!
      int newCapacity = oldCapacity + (oldCapacity >> 1) + 1;
      if (newCapacity < minCapacity) {

   * equivalent to RegularImmutableSet, save that instead of having a hash table containing the
   * elements directly and null for empty positions, we store indices of the keys in the hash table,
   * and ABSENT for empty positions.  We then look up the keys in alternatingKeysAndValues.
   *
   * (The index actually stored is the index of the key in alternatingKeysAndValues, which is

 * associated with a key and then add the key back to the multimap, that key will come last in the
 * key iteration order.
 *
 * <p>The multimap does not store duplicate key-value pairs. Adding a new key-value pair equal to an
 * existing key-value pair has no effect.
 *
 * <p>Keys and values may be null. All optional multimap methods are supported, and all returned

 *   <li>To distinguish between "unknown" (for example, not present in a map) and "known to have no
 *       value" (present in the map, with value {@code Optional.absent()})
 *   <li>To wrap nullable references for storage in a collection that does not support {@code null}
 *       (though there are <a
 *       href="https://github.com/google/guava/wiki/LivingWithNullHostileCollections">several other

      }
    }
    return true;
  }

  /**
   * Each instance of MinMaxPriorityQueue encapsulates two instances of Heap: a min-heap and a
   * max-heap. Conceptually, these might each have their own array for storage, but for efficiency's
   * sake they are stored interleaved on alternate heap levels in the same array (MMPQ.queue).
   */
  @WeakOuter
  class Heap {
    final Ordering<E> ordering;

      incidental, or consequential damages of any character arising as a
      result of this License or out of the use or inability to use the
      Work (including but not limited to damages for loss of goodwill,
      work stoppage, computer failure or malfunction, or any and all
      other commercial damages or losses), even if such Contributor
      has been advised of the possibility of such damages.

import java.util.Map;
import java.util.Set;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Implementation of {@link Multimap} using hash tables.
 *
 * <p>The multimap does not store duplicate key-value pairs. Adding a new key-value pair equal to an
 * existing key-value pair has no effect.
 *
 * <p>Keys and values may be null. All optional multimap methods are supported, and all returned

import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Implementation of {@code Multimap} that uses an {@code ArrayList} to store the values for a given
 * key. A {@link HashMap} associates each key with an {@link ArrayList} of values.
 *
 * <p>When iterating through the collections supplied by this class, the ordering of values for a

    this.setEntry(entryIndex, CompactHashing.maskCombine(hash, UNSET, mask));
    this.setKey(entryIndex, key);
    this.setValue(entryIndex, value);
  }

  /** Resizes the entries storage if necessary. */
  private void resizeMeMaybe(int newSize) {
    int entriesSize = requireEntries().length;
    if (newSize > entriesSize) {