import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import junit.framework.AssertionFailedError;
import junit.framework.TestCase;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Unit test for {@link Preconditions}.
 *
 * @author Kevin Bourrillion
 * @author Jared Levy
 */
@ElementTypesAreNonnullByDefault

import java.util.List;
import java.util.Map.Entry;
import java.util.Set;
import junit.framework.Test;
import junit.framework.TestCase;
import junit.framework.TestSuite;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Unit tests for {@code LinkedHashMultimap}.
 *
 * @author Jared Levy
 */
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
public class LinkedHashMultimapTest extends TestCase {

import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import junit.framework.Test;
import junit.framework.TestCase;
import junit.framework.TestSuite;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Unit test for {@link ImmutableList}.
 *
 * @author Kevin Bourrillion
 * @author George van den Driessche
 * @author Jared Levy
 */
@GwtCompatible(emulated = true)

import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.atomic.AtomicInteger;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A multiset that supports concurrent modifications and that provides atomic versions of most
 * {@code Multiset} operations (exceptions where noted). Null elements are not supported.
 *

import com.google.common.annotations.VisibleForTesting;
import java.util.AbstractMap;
import java.util.Arrays;
import java.util.Map.Entry;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A hash-based implementation of {@link ImmutableMap}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible(serializable = true, emulated = true)
@ElementTypesAreNonnullByDefault

import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicReference;
import org.checkerframework.checker.nullness.qual.Nullable;
import org.mockito.InOrder;
import org.mockito.Mockito;

/**
 * Tests for MoreExecutors.
 *
 * @author Kyle Littlefield (klittle)
 */
public class MoreExecutorsTest extends JSR166TestCase {

---

O ponto principal é que **nenhum** desses são **regras escritas em pedra** que você deve seguir cegamente. Você pode usar essas idéias para **avaliar seu próprio caso de uso** e decidir qual é a melhor abordagem para seu sistema, verificando como gerenciar os conceitos de:

* Segurança - HTTPS
* Executando na inicialização
* Reinicializações
* Replicação (o número de processos em execução)
* Memória

import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.checkerframework.checker.nullness.qual.Nullable;
import sun.misc.Unsafe;

/** Benchmarks for {@link ExecutionList}. */
@VmOptions({"-Xms8g", "-Xmx8g"})
public class ExecutionListBenchmark {
  private static final int NUM_THREADS = 10; // make a param?

import java.util.Set;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A future whose value is derived from a collection of input futures.
 *
 * @param <InputT> the type of the individual inputs
 * @param <OutputT> the type of the output (i.e. this) future
 */

        // We have metadata retrieval problems, or there are cycles that have been detected
        // so we give this back to the calling code and let them deal with this information
        // appropriately.

        if (result.hasMetadataResolutionExceptions()
                || result.hasVersionRangeViolations()
                || result.hasCircularDependencyExceptions()) {