public ImmutableSortedMap<K, V> descendingMap() {
    // TODO(kevinb): The descendingMap is never actually cached at all. Either:
    //
    // - Cache it, and annotate the field with @LazyInit.
    // - Simplify the code below, and consider eliminating the field (b/287198172), which is also
    //   set by one of the constructors.
    ImmutableSortedMap<K, V> result = descendingMap;
    if (result == null) {
      if (isEmpty()) {

    Waiter(boolean unused) {}

    Waiter() {
      // avoid volatile write, write is made visible by subsequent CAS on waiters field
      ATOMIC_HELPER.putThread(this, Thread.currentThread());
    }

    // non-volatile write to the next field. Should be made visible by subsequent CAS on waiters
    // field.
    void setNext(@CheckForNull Waiter next) {
      ATOMIC_HELPER.putNext(this, next);
    }

    void unpark() {

     * purposes, the "count" field, tracking the number of elements, serves as that volatile
     * variable ensuring visibility. This is convenient because this field needs to be read in many
     * read operations anyway:
     *
     * - All (unsynchronized) read operations must first read the "count" field, and should not
     * look at table entries if it is 0.
     *

import com.google.common.truth.IterableSubject;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.io.Serializable;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.GenericArrayType;
import java.lang.reflect.Method;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.lang.reflect.TypeVariable;

  // final fields.
  //
  // For simplicity the rest of this description will discuss Futures.catching since it is the
  // simplest instance, though very similar descriptions apply to many other classes in this file.
  //
  // In the constructor of AbstractCatchingFuture, the delegate future is assigned to a field
  // 'inputFuture'. That field is non-final and non-volatile. There are 2 places where the

   * usually have much noticeable impact. A value of one permits only one thread to modify the cache
   * at a time, but since read operations and cache loading computations can proceed concurrently,
   * this still yields higher concurrency than full synchronization.
   *
   * <p>Defaults to 4. <b>Note:</b>The default may change in the future. If you care about this
   * value, you should always choose it explicitly.
   *

  /**
   * Divides an iterator into unmodifiable sublists of the given size (the final list may be
   * smaller). For example, partitioning an iterator containing {@code [a, b, c, d, e]} with a
   * partition size of 3 yields {@code [[a, b, c], [d, e]]} -- an outer iterator containing two
   * inner lists of three and two elements, all in the original order.
   *
   * <p>The returned lists implement {@link java.util.RandomAccess}.
   *

  /**
   * Divides an iterator into unmodifiable sublists of the given size (the final list may be
   * smaller). For example, partitioning an iterator containing {@code [a, b, c, d, e]} with a
   * partition size of 3 yields {@code [[a, b, c], [d, e]]} -- an outer iterator containing two
   * inner lists of three and two elements, all in the original order.
   *
   * <p>The returned lists implement {@link java.util.RandomAccess}.
   *

import com.google.common.truth.IterableSubject;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.io.Serializable;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.GenericArrayType;
import java.lang.reflect.Method;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.lang.reflect.TypeVariable;