Address some https://errorprone.info/bugpattern/JdkObsolete warnings.

It turns out that we'd changed our choice of `Queue` in `MultimapsTest` once previously in cl/16428259 _without updating the clever comment about it later in the file_ 😱

RELNOTES=n/a
PiperOrigin-RevId: 726065051

Author: cpovirk

android/guava-testlib/src/com/google/common/collect/testing/TestsForListsInJavaUtil.java

@@ -188,6 +188,8 @@ public List<String> create(String[] elements) {
         .createTestSuite();
   }
 
+  // We are testing LinkedList / testing our tests on LinkedList.
+  @SuppressWarnings("JdkObsolete")
   public Test testsForLinkedList() {
     return ListTestSuiteBuilder.using(
             new TestStringListGenerator() {
@@ -322,6 +324,8 @@ public ListIterator<String> listIterator(int index) {
         .createTestSuite();
   }
 
+  // We are testing Vector / testing our tests on Vector.
+  @SuppressWarnings("JdkObsolete")
   private Test testsForVector() {
     return ListTestSuiteBuilder.using(
             new TestStringListGenerator() {

android/guava-testlib/src/com/google/common/collect/testing/TestsForMapsInJavaUtil.java

@@ -246,6 +246,8 @@ public Test testsForHashtable() {
     return MapTestSuiteBuilder.using(
             new TestStringMapGenerator() {
               @Override
+              // We are testing Hashtable / testing our tests on Hashtable.
+              @SuppressWarnings("JdkObsolete")
               protected Map<String, String> create(Entry<String, String>[] entries) {
                 return populate(new Hashtable<String, String>(), entries);
               }

android/guava-testlib/src/com/google/common/collect/testing/TestsForQueuesInJavaUtil.java

@@ -111,6 +111,8 @@ public Test testsForLinkedList() {
     return QueueTestSuiteBuilder.using(
             new TestStringQueueGenerator() {
               @Override
+              // We are testing LinkedList / testing our tests on LinkedList.
+              @SuppressWarnings("JdkObsolete")
               public Queue<String> create(String[] elements) {
                 return new LinkedList<>(MinimalCollection.of(elements));
               }

android/guava-testlib/src/com/google/common/testing/TearDownStack.java

@@ -22,8 +22,9 @@
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.collect.Lists;
 import com.google.errorprone.annotations.concurrent.GuardedBy;
+import java.util.ArrayDeque;
 import java.util.ArrayList;
-import java.util.LinkedList;
+import java.util.Deque;
 import java.util.List;
 import java.util.logging.Level;
 import java.util.logging.Logger;
@@ -45,7 +46,7 @@ public class TearDownStack implements TearDownAccepter {
   @VisibleForTesting final Object lock = new Object();
 
   @GuardedBy("lock")
-  final LinkedList<TearDown> stack = new LinkedList<>();
+  final Deque<TearDown> stack = new ArrayDeque<>();
 
   private final boolean suppressThrows;
 

android/guava-tests/test/com/google/common/collect/IterablesTest.java

@@ -1234,11 +1234,12 @@ public boolean apply(CharSequence input) {
         }
       };
 
+  @SuppressWarnings("UnnecessaryStringBuilder") // false positive in a weird case
   public void testIndexOf_genericPredicate() {
     List<CharSequence> sequences = Lists.newArrayList();
     sequences.add("bob");
     sequences.add(new StringBuilder("charlie"));
-    sequences.add(new StringBuffer("henry"));
+    sequences.add(new StringBuilder("henry"));
     sequences.add(new StringBuilder("apple"));
     sequences.add("lemon");
 

android/guava-tests/test/com/google/common/collect/IteratorsTest.java

@@ -1158,6 +1158,8 @@ public void testAsEnumerationTypical() {
     assertFalse(enumer.hasMoreElements());
   }
 
+  // We're testing our asEnumeration method against a known-good implementation.
+  @SuppressWarnings("JdkObsolete")
   private static Enumeration<Integer> enumerate(int... ints) {
     Vector<Integer> vector = new Vector<>(Ints.asList(ints));
     return vector.elements();

android/guava-tests/test/com/google/common/collect/ListsImplTest.java

@@ -266,6 +266,8 @@ protected LinkedListExample(String name) {
     }
 
     @Override
+    // We are testing our utilities on LinkedList.
+    @SuppressWarnings("JdkObsolete")
     public <T> List<T> createList(Class<T> listType, Collection<? extends T> contents) {
       return new LinkedList<>(contents);
     }

android/guava-tests/test/com/google/common/collect/MultimapsTest.java

@@ -543,6 +543,11 @@ public E get() {
 
   private static class QueueSupplier extends CountingSupplier<Queue<Integer>> {
     @Override
+    /*
+     * We need a Queue that implements equals() for the equality tests we perform after
+     * reserializing the multimap.
+     */
+    @SuppressWarnings("JdkObsolete")
     public Queue<Integer> getImpl() {
       return new LinkedList<>();
     }
@@ -587,7 +592,7 @@ public boolean addAll(Collection<? extends Integer> collection) {
   }
 
   public void testNewMultimap() {
-    // The ubiquitous EnumArrayBlockingQueueMultimap
+    // The ubiquitous EnumLinkedListMultimap
     CountingSupplier<Queue<Integer>> factory = new QueueSupplier();
 
     Map<Color, Collection<Integer>> map = Maps.newEnumMap(Color.class);

android/guava/src/com/google/common/collect/ForwardingSortedMap.java

@@ -50,6 +50,11 @@
  * @since 2.0
  */
 @GwtCompatible
+/*
+ * We provide and encourage use of ForwardingNavigableSet over this class, but we still provide this
+ * one to preserve compatibility.
+ */
+@SuppressWarnings("JdkObsolete")
 public abstract class ForwardingSortedMap<K extends @Nullable Object, V extends @Nullable Object>
     extends ForwardingMap<K, V> implements SortedMap<K, V> {
   // TODO(lowasser): identify places where thread safety is actually lost

android/guava/src/com/google/common/collect/ForwardingSortedSet.java

@@ -53,6 +53,11 @@
  * @since 2.0
  */
 @GwtCompatible
+/*
+ * We provide and encourage use of ForwardingNavigableSet over this class, but we still provide this
+ * one to preserve compatibility.
+ */
+@SuppressWarnings("JdkObsolete")
 public abstract class ForwardingSortedSet<E extends @Nullable Object> extends ForwardingSet<E>
     implements SortedSet<E> {
 

android/guava/src/com/google/common/collect/Iterators.java

@@ -1159,6 +1159,8 @@ public T next() {
    * <p>The {@code Iterable} equivalent of this method is either {@link Collections#enumeration} (if
    * you have a {@link Collection}), or {@code Iterators.asEnumeration(collection.iterator())}.
    */
+  // This is an adapter for cases in which users do need an Enumeration for whatever reason.
+  @SuppressWarnings("JdkObsolete")
   public static <T extends @Nullable Object> Enumeration<T> asEnumeration(Iterator<T> iterator) {
     checkNotNull(iterator);
     return new Enumeration<T>() {

android/guava/src/com/google/common/collect/Lists.java

@@ -226,7 +226,10 @@ static int computeArrayListCapacity(int arraySize) {
    * syntax</a>.
    */
   @GwtCompatible(serializable = true)
-  @SuppressWarnings("NonApiType") // acts as a direct substitute for a constructor call
+  @SuppressWarnings({
+    "NonApiType", // acts as a direct substitute for a constructor call
+    "JdkObsolete", // We recommend against this method but need to keep it for compatibility.
+  })
   public static <E extends @Nullable Object> LinkedList<E> newLinkedList() {
     return new LinkedList<>();
   }

android/guava/src/com/google/common/collect/MultimapBuilder.java

@@ -203,6 +203,8 @@ private enum LinkedListSupplier implements Supplier<List<?>> {
     }
 
     @Override
+    // We recommend against linkedListValues but need to keep it for compatibility.
+    @SuppressWarnings("JdkObsolete")
     public List<?> get() {
       return new LinkedList<>();
     }
@@ -302,7 +304,15 @@ public abstract static class MultimapBuilderWithKeys<K0 extends @Nullable Object
       };
     }
 
-    /** Uses a {@link LinkedList} to store value collections. */
+    /**
+     * Uses a {@link LinkedList} to store value collections.
+     *
+     * <p><b>Performance note:</b> {@link ArrayList} and {@link java.util.ArrayDeque} consistently
+     * outperform {@code LinkedList} except in certain rare and specific situations. Unless you have
+     * spent a lot of time benchmarking your specific needs, use one of those instead. (However, we
+     * do not currently offer a {@link Multimap} implementation based on {@link
+     * java.util.ArrayDeque}.)
+     */
     public ListMultimapBuilder<K0, @Nullable Object> linkedListValues() {
       return new ListMultimapBuilder<K0, @Nullable Object>() {
         @Override

guava-testlib/src/com/google/common/collect/testing/TestsForListsInJavaUtil.java

@@ -192,6 +192,8 @@ public List<String> create(String[] elements) {
         .createTestSuite();
   }
 
+  // We are testing LinkedList / testing our tests on LinkedList.
+  @SuppressWarnings("JdkObsolete")
   public Test testsForLinkedList() {
     return ListTestSuiteBuilder.using(
             new TestStringListGenerator() {
@@ -326,6 +328,8 @@ public ListIterator<String> listIterator(int index) {
         .createTestSuite();
   }
 
+  // We are testing Vector / testing our tests on Vector.
+  @SuppressWarnings("JdkObsolete")
   private Test testsForVector() {
     return ListTestSuiteBuilder.using(
             new TestStringListGenerator() {

guava-testlib/src/com/google/common/collect/testing/TestsForMapsInJavaUtil.java

@@ -324,6 +324,8 @@ public Test testsForHashtable() {
     return MapTestSuiteBuilder.using(
             new TestStringMapGenerator() {
               @Override
+              // We are testing Hashtable / testing our tests on Hashtable.
+              @SuppressWarnings("JdkObsolete")
               protected Map<String, String> create(Entry<String, String>[] entries) {
                 return populate(new Hashtable<String, String>(), entries);
               }

guava-testlib/src/com/google/common/collect/testing/TestsForQueuesInJavaUtil.java

@@ -144,6 +144,8 @@ public Test testsForLinkedList() {
     return QueueTestSuiteBuilder.using(
             new TestStringQueueGenerator() {
               @Override
+              // We are testing LinkedList / testing our tests on LinkedList.
+              @SuppressWarnings("JdkObsolete")
               public Queue<String> create(String[] elements) {
                 return new LinkedList<>(MinimalCollection.of(elements));
               }

guava-testlib/src/com/google/common/testing/TearDownStack.java

@@ -22,8 +22,9 @@
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.collect.Lists;
 import com.google.errorprone.annotations.concurrent.GuardedBy;
+import java.util.ArrayDeque;
 import java.util.ArrayList;
-import java.util.LinkedList;
+import java.util.Deque;
 import java.util.List;
 import java.util.logging.Level;
 import java.util.logging.Logger;
@@ -45,7 +46,7 @@ public class TearDownStack implements TearDownAccepter {
   @VisibleForTesting final Object lock = new Object();
 
   @GuardedBy("lock")
-  final LinkedList<TearDown> stack = new LinkedList<>();
+  final Deque<TearDown> stack = new ArrayDeque<>();
 
   private final boolean suppressThrows;
 

guava-tests/benchmark/com/google/common/collect/StreamsBenchmark.java

@@ -40,6 +40,8 @@ public class StreamsBenchmark {
   @Param({"1", "10", "100", "1000", "10000"})
   private int size;
 
+  // This is a benchmark of streams, including those from LinkedList.
+  @SuppressWarnings("JdkObsolete")
   enum CollectionType {
     ARRAY_LIST(ArrayList::new),
     LINKED_LIST(LinkedList::new);

guava-tests/test/com/google/common/collect/IterablesTest.java

@@ -1271,11 +1271,12 @@ public boolean apply(CharSequence input) {
         }
       };
 
+  @SuppressWarnings("UnnecessaryStringBuilder") // false positive in a weird case
   public void testIndexOf_genericPredicate() {
     List<CharSequence> sequences = Lists.newArrayList();
     sequences.add("bob");
     sequences.add(new StringBuilder("charlie"));
-    sequences.add(new StringBuffer("henry"));
+    sequences.add(new StringBuilder("henry"));
     sequences.add(new StringBuilder("apple"));
     sequences.add("lemon");
 

guava-tests/test/com/google/common/collect/IteratorsTest.java

@@ -1158,6 +1158,8 @@ public void testAsEnumerationTypical() {
     assertFalse(enumer.hasMoreElements());
   }
 
+  // We're testing our asEnumeration method against a known-good implementation.
+  @SuppressWarnings("JdkObsolete")
   private static Enumeration<Integer> enumerate(int... ints) {
     Vector<Integer> vector = new Vector<>(Ints.asList(ints));
     return vector.elements();

guava-tests/test/com/google/common/collect/ListsImplTest.java

@@ -266,6 +266,8 @@ protected LinkedListExample(String name) {
     }
 
     @Override
+    // We are testing our utilities on LinkedList.
+    @SuppressWarnings("JdkObsolete")
     public <T> List<T> createList(Class<T> listType, Collection<? extends T> contents) {
       return new LinkedList<>(contents);
     }

guava-tests/test/com/google/common/collect/MultimapsTest.java

@@ -614,6 +614,11 @@ public E get() {
 
   private static class QueueSupplier extends CountingSupplier<Queue<Integer>> {
     @Override
+    /*
+     * We need a Queue that implements equals() for the equality tests we perform after
+     * reserializing the multimap.
+     */
+    @SuppressWarnings("JdkObsolete")
     public Queue<Integer> getImpl() {
       return new LinkedList<>();
     }
@@ -658,7 +663,7 @@ public boolean addAll(Collection<? extends Integer> collection) {
   }
 
   public void testNewMultimap() {
-    // The ubiquitous EnumArrayBlockingQueueMultimap
+    // The ubiquitous EnumLinkedListMultimap
     CountingSupplier<Queue<Integer>> factory = new QueueSupplier();
 
     Map<Color, Collection<Integer>> map = Maps.newEnumMap(Color.class);

guava-tests/test/com/google/common/collect/StreamsTest.java

@@ -92,6 +92,7 @@ public void testFindLast_refStream() {
     assertThat(findLast(Stream.of("a", "b", "c", "d"))).hasValue("d");
 
     // test with a large, not-subsized Spliterator
+    @SuppressWarnings("JdkObsolete")
     List<Integer> list =
         IntStream.rangeClosed(0, 10000).boxed().collect(Collectors.toCollection(LinkedList::new));
     assertThat(findLast(list.stream())).hasValue(10000);
@@ -105,6 +106,7 @@ public void testFindLast_intStream() {
     assertThat(findLast(IntStream.of(1, 2, 3, 4, 5))).isEqualTo(OptionalInt.of(5));
 
     // test with a large, not-subsized Spliterator
+    @SuppressWarnings("JdkObsolete")
     List<Integer> list =
         IntStream.rangeClosed(0, 10000).boxed().collect(Collectors.toCollection(LinkedList::new));
     assertThat(findLast(list.stream().mapToInt(i -> i))).isEqualTo(OptionalInt.of(10000));
@@ -119,6 +121,7 @@ public void testFindLast_longStream() {
     assertThat(findLast(LongStream.of(1, 2, 3, 4, 5))).isEqualTo(OptionalLong.of(5));
 
     // test with a large, not-subsized Spliterator
+    @SuppressWarnings("JdkObsolete")
     List<Long> list =
         LongStream.rangeClosed(0, 10000).boxed().collect(Collectors.toCollection(LinkedList::new));
     assertThat(findLast(list.stream().mapToLong(i -> i))).isEqualTo(OptionalLong.of(10000));
@@ -133,6 +136,7 @@ public void testFindLast_doubleStream() {
     assertThat(findLast(DoubleStream.of(1, 2, 3, 4, 5))).isEqualTo(OptionalDouble.of(5));
 
     // test with a large, not-subsized Spliterator
+    @SuppressWarnings("JdkObsolete")
     List<Long> list =
         LongStream.rangeClosed(0, 10000).boxed().collect(Collectors.toCollection(LinkedList::new));
     assertThat(findLast(list.stream().mapToDouble(i -> i))).isEqualTo(OptionalDouble.of(10000));

guava/src/com/google/common/collect/ForwardingSortedMap.java

@@ -50,6 +50,11 @@
  * @since 2.0
  */
 @GwtCompatible
+/*
+ * We provide and encourage use of ForwardingNavigableSet over this class, but we still provide this
+ * one to preserve compatibility.
+ */
+@SuppressWarnings("JdkObsolete")
 public abstract class ForwardingSortedMap<K extends @Nullable Object, V extends @Nullable Object>
     extends ForwardingMap<K, V> implements SortedMap<K, V> {
   // TODO(lowasser): identify places where thread safety is actually lost

guava/src/com/google/common/collect/ForwardingSortedSet.java

@@ -53,6 +53,11 @@
  * @since 2.0
  */
 @GwtCompatible
+/*
+ * We provide and encourage use of ForwardingNavigableSet over this class, but we still provide this
+ * one to preserve compatibility.
+ */
+@SuppressWarnings("JdkObsolete")
 public abstract class ForwardingSortedSet<E extends @Nullable Object> extends ForwardingSet<E>
     implements SortedSet<E> {
 

guava/src/com/google/common/collect/Iterators.java

@@ -1159,6 +1159,8 @@ public T next() {
    * <p>The {@code Iterable} equivalent of this method is either {@link Collections#enumeration} (if
    * you have a {@link Collection}), or {@code Iterators.asEnumeration(collection.iterator())}.
    */
+  // This is an adapter for cases in which users do need an Enumeration for whatever reason.
+  @SuppressWarnings("JdkObsolete")
   public static <T extends @Nullable Object> Enumeration<T> asEnumeration(Iterator<T> iterator) {
     checkNotNull(iterator);
     return new Enumeration<T>() {

guava/src/com/google/common/collect/Lists.java

@@ -227,7 +227,10 @@ static int computeArrayListCapacity(int arraySize) {
    * syntax</a>.
    */
   @GwtCompatible(serializable = true)
-  @SuppressWarnings("NonApiType") // acts as a direct substitute for a constructor call
+  @SuppressWarnings({
+    "NonApiType", // acts as a direct substitute for a constructor call
+    "JdkObsolete", // We recommend against this method but need to keep it for compatibility.
+  })
   public static <E extends @Nullable Object> LinkedList<E> newLinkedList() {
     return new LinkedList<>();
   }

guava/src/com/google/common/collect/MultimapBuilder.java

@@ -203,6 +203,8 @@ private enum LinkedListSupplier implements Supplier<List<?>> {
     }
 
     @Override
+    // We recommend against linkedListValues but need to keep it for compatibility.
+    @SuppressWarnings("JdkObsolete")
     public List<?> get() {
       return new LinkedList<>();
     }
@@ -302,7 +304,15 @@ public abstract static class MultimapBuilderWithKeys<K0 extends @Nullable Object
       };
     }
 
-    /** Uses a {@link LinkedList} to store value collections. */
+    /**
+     * Uses a {@link LinkedList} to store value collections.
+     *
+     * <p><b>Performance note:</b> {@link ArrayList} and {@link java.util.ArrayDeque} consistently
+     * outperform {@code LinkedList} except in certain rare and specific situations. Unless you have
+     * spent a lot of time benchmarking your specific needs, use one of those instead. (However, we
+     * do not currently offer a {@link Multimap} implementation based on {@link
+     * java.util.ArrayDeque}.)
+     */
     public ListMultimapBuilder<K0, @Nullable Object> linkedListValues() {
       return new ListMultimapBuilder<K0, @Nullable Object>() {
         @Override