}
          case SET_COUNT:
            {
              int newValue = random.nextInt(3);
              int oldValue = multiset.setCount(key, newValue);
              deltas[keyIndex] += newValue - oldValue;
              break;
            }
          case SET_COUNT_IF:
            {
              int newValue = random.nextInt(3);
              int oldValue = multiset.count(key);

        Map<String, Object> parentMap = new HashMap<>();
        DocMap docMap = new DocMap(parentMap);

        assertNull(docMap.put("newKey", "newValue"));
        assertEquals("newValue", docMap.get("newKey"));

        assertEquals("newValue", docMap.put("newKey", "updatedValue"));
        assertEquals("updatedValue", docMap.get("newKey"));

        assertNull(docMap.get("nonexistent"));
    }

  private static void putThread(Waiter waiter, Thread newValue) {
    ATOMIC_HELPER.putThread(waiter, newValue);
  }

  /** Non-volatile write of the waiter to the {@link Waiter#next} field. */
  private static void putNext(Waiter waiter, @Nullable Waiter newValue) {
    ATOMIC_HELPER.putNext(waiter, newValue);
  }

  /**

  private static void putThread(Waiter waiter, Thread newValue) {
    ATOMIC_HELPER.putThread(waiter, newValue);
  }

  /** Non-volatile write of the waiter to the {@link Waiter#next} field. */
  private static void putNext(Waiter waiter, @Nullable Waiter newValue) {
    ATOMIC_HELPER.putNext(waiter, newValue);
  }

  /**

  }

  /**
   * Associates {@code newValue} with {@code key} in this map, and returns the value previously
   * associated with {@code key}, or zero if there was no such value.
   */
  @CanIgnoreReturnValue
  public long put(K key, long newValue) {
    return getAndUpdate(key, x -> newValue);
  }

  /**

    assertFalse(segment.replace(key, hash, oldValue, newValue));
    assertEquals(0, segment.count);

    // same value
    table.set(index, entry);
    segment.count++;
    assertEquals(1, segment.count);
    assertSame(oldValue, segment.get(key, hash));
    assertTrue(segment.replace(key, hash, oldValue, newValue));
    assertEquals(1, segment.count);
    assertSame(newValue, segment.get(key, hash));

    doTestSet(e3());
  }

  private void doTestSet(E newValue) {
    int index = aValidIndex();
    E initialValue = getList().get(index);
    assertEquals(
        "set(i, x) should return the old element at position i.",
        initialValue,
        getList().set(index, newValue));
    assertEquals("After set(i, x), get(i) should return x", newValue, getList().get(index));

           * nullness checker.
           */
          K key = keyFunction.apply(t);
          V newValue = valueFunction.apply(t);
          accum.put(
              checkNotNull(key, "Null key for input %s", t),
              checkNotNull(newValue, "Null value for input %s", t));
        },
        EnumMapAccumulator::combine,
        EnumMapAccumulator::toImmutableMap,

           * nullness checker.
           */
          K key = keyFunction.apply(t);
          V newValue = valueFunction.apply(t);
          accum.put(
              checkNotNull(key, "Null key for input %s", t),
              checkNotNull(newValue, "Null value for input %s", t));
        },
        EnumMapAccumulator::combine,
        EnumMapAccumulator::toImmutableMap,

    }

    @Override
    @Nullable V getValue(int index) {
      return at(index, columnIndex);
    }

    @Override
    @Nullable V setValue(int index, @Nullable V newValue) {
      return set(index, columnIndex, newValue);
    }
  }

  /**
   * Returns an immutable set of the valid column keys, including those that are associated with
   * null values only.
   *