Object key = new Object();
    assertThat(cache.getUnchecked(key)).isNotNull();

    CacheTesting.simulateValueReclamation(cache, key);

    // this blocks if computation can't deal with partially-collected values
    assertThat(cache.getUnchecked(key)).isNotNull();
    assertThat(cache.size()).isEqualTo(1);
    assertThat(countingLoader.getCount()).isEqualTo(2);

 * <i>if and only if</i> {@code a.equals(b)}. If this advice is not followed, the resulting
 * collection will not correctly obey its specification.
 *
 * <p>See the Guava User Guide article on <a href=
 * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>.
 *
 * @author Louis Wasserman
 * @since 12.0
 */
@GwtIncompatible // hasn't been tested yet

---
title: "Go, Backwards Compatibility, and GODEBUG"
layout: article
---

<!--
This document is kept in the Go repo, not x/website,
because it documents the full list of known GODEBUG settings,
which are tied to a specific release.
-->

## Introduction {#intro}

Go's emphasis on backwards compatibility is one of its key strengths.
There are, however, times when we cannot maintain complete compatibility.

import org.jspecify.annotations.Nullable;

/**
 * Static utility methods pertaining to {@code long} primitives, that are not already found in
 * either {@link Long} or {@link Arrays}.
 *
 * <p>See the Guava User Guide article on <a
 * href="https://github.com/google/guava/wiki/PrimitivesExplained">primitive utilities</a>.
 *
 * @author Kevin Bourrillion
 * @since 1.0
 */
@GwtCompatible
public final class Longs {
  private Longs() {}

import org.jspecify.annotations.Nullable;

/**
 * A {@link List} whose contents will never change, with many other important properties detailed at
 * {@link ImmutableCollection}.
 *
 * <p>See the Guava User Guide article on <a href=
 * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>.
 *
 * @see ImmutableMap
 * @see ImmutableSet
 * @author Kevin Bourrillion
 * @since 2.0
 */

/**
 * Static utility methods pertaining to {@link List} instances. Also see this class's counterparts
 * {@link Sets}, {@link Maps} and {@link Queues}.
 *
 * <p>See the Guava User Guide article on <a href=
 * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#lists">{@code Lists}</a>.
 *
 * @author Kevin Bourrillion
 * @author Mike Bostock
 * @author Louis Wasserman
 * @since 2.0
 */

/**
 * Static utility methods pertaining to {@link Set} instances. Also see this class's counterparts
 * {@link Lists}, {@link Maps} and {@link Queues}.
 *
 * <p>See the Guava User Guide article on <a href=
 * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#sets">{@code Sets}</a>.
 *
 * @author Kevin Bourrillion
 * @author Jared Levy
 * @author Chris Povirk
 * @since 2.0
 */

				if opts.LatestOnly {
					requestedVersions = 1
				}

				// However many we ask, versions must exist on ~50%
				listingQuorum := (askDisks + 1) / 2

				// How to resolve partial results.
				resolver := metadataResolutionParams{
					dirQuorum:         listingQuorum,
					objQuorum:         listingQuorum,
					bucket:            bucket,
					requestedVersions: requestedVersions,
				}

		cache.iamUserPolicyMap = newCache.iamUserPolicyMap
		cache.iamUsersMap = newCache.iamUsersMap
		// For STS policy map, we need to merge the new cache with the existing
		// cache because the periodic IAM reload is partial. The periodic load
		// here is to account for STS policy mapping changes that should apply
		// for service accounts derived from such STS accounts (i.e. LDAP STS
		// accounts).

 * are <i>lazy</i>, which means that their iterators only advance the backing iteration when
 * absolutely necessary.
 *
 * <p>See the Guava User Guide article on <a href=
 * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#iterables">{@code
 * Iterables}</a>.
 *
 * @author Kevin Bourrillion
 * @author Jared Levy
 * @since 2.0
 */
@GwtCompatible