Use @NullMarked instead of our custom `@ElementTypesAreNonnullByDef…

…ault` annotations.

This is the first step toward [using JSpecify in Guava](jspecify/jspecify#239 (comment)). At the end of that path, we'll be able to [remove our dependency on JSR-305](#2960) (and on the Checker Framework's annotations), and we'll have one less blocker to [providing a `module-info`](#2970).

`@NullMarked` allows tools like kotlinc to produce errors for code like `ImmutableList<String?>`. (Before releasing this change, I'll conduct some further testing to more fully characterize the effects, both under Kotlin 2.1 and prior.) As we make further changes, it will allow kotlinc to detect even more nullness problems. We will make these changes in a series of incremental releases so that users can pick them up gradually, as we did inside Google. In simple cases, users may wish to pick up all the changes at once instead by upgrading straight from Guava 33.4.0 (or an earlier version) to Guava 33.4.4 (or whatever the version to make the final changes ends up being).

RELNOTES=Replaced our custom `@ElementTypesAreNonnullByDefault` annotations with the JSpecify `@NullMarked` annotation.
PiperOrigin-RevId: 707134516

android/guava-testlib/pom.xml

@@ -14,6 +14,10 @@
     unit testing - particularly to assist the tests for Guava itself.
   </description>
   <dependencies>
+    <dependency>
+      <groupId>org.jspecify</groupId>
+      <artifactId>jspecify</artifactId>
+    </dependency>
     <dependency>
       <groupId>com.google.code.findbugs</groupId>
       <artifactId>jsr305</artifactId>

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

@@ -32,7 +32,6 @@
 @Ignore("test runners must not instantiate and run this directly, only via suites we build")
 // @Ignore affects the Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.
 @SuppressWarnings("JUnit4ClassUsedInJUnit3")
-@ElementTypesAreNonnullByDefault
 public abstract class AbstractCollectionTester<E extends @Nullable Object>
     extends AbstractContainerTester<Collection<E>, E> {
 

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

@@ -42,7 +42,6 @@
 @Ignore("test runners must not instantiate and run this directly, only via suites we build")
 // @Ignore affects the Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.
 @SuppressWarnings("JUnit4ClassUsedInJUnit3")
-@ElementTypesAreNonnullByDefault
 public abstract class AbstractContainerTester<C, E extends @Nullable Object>
     extends AbstractTester<OneSizeTestContainerGenerator<C, E>> {
   protected SampleElements<E> samples;

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

@@ -45,7 +45,6 @@
  * @author Chris Povirk
  */
 @GwtCompatible
-@ElementTypesAreNonnullByDefault
 abstract class AbstractIteratorTester<E extends @Nullable Object, I extends Iterator<E>> {
   private Stimulus<E, ? super I>[] stimuli;
   private final Iterator<E> elementsToInsert;

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

@@ -43,7 +43,6 @@
 @Ignore("test runners must not instantiate and run this directly, only via suites we build")
 // @Ignore affects the Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.
 @SuppressWarnings("JUnit4ClassUsedInJUnit3")
-@ElementTypesAreNonnullByDefault
 public abstract class AbstractMapTester<K extends @Nullable Object, V extends @Nullable Object>
     extends AbstractContainerTester<Map<K, V>, Entry<K, V>> {
   protected Map<K, V> getMap() {

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

@@ -34,7 +34,6 @@
  * @author George van den Driessche
  */
 @GwtCompatible(emulated = true)
-@ElementTypesAreNonnullByDefault
 public class AbstractTester<G> extends TestCase {
   private G subjectGenerator;
   private String suiteName;

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

@@ -41,7 +41,6 @@
  * @author George van den Driessche
  */
 @GwtCompatible
-@ElementTypesAreNonnullByDefault
 public final class DerivedCollectionGenerators {
   public static class MapEntrySetGenerator<K extends @Nullable Object, V extends @Nullable Object>
       implements TestSetGenerator<Entry<K, V>>, DerivedGenerator {

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

@@ -47,7 +47,6 @@
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 @GwtCompatible(emulated = true)
-@ElementTypesAreNonnullByDefault
 public class Helpers {
   // Clone of Objects.equal
   static boolean equal(@Nullable Object a, @Nullable Object b) {

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

@@ -26,5 +26,4 @@
  * <p>Each package's copy of this annotation needs to be listed in our {@code pom.xml}.
  */
 @Target({METHOD, CONSTRUCTOR, TYPE})
-@ElementTypesAreNonnullByDefault
 @interface IgnoreJRERequirement {}

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

@@ -85,7 +85,6 @@
  * @author Chris Povirk
  */
 @GwtCompatible
-@ElementTypesAreNonnullByDefault
 public abstract class IteratorTester<E extends @Nullable Object>
     extends AbstractIteratorTester<E, Iterator<E>> {
   /**

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

@@ -36,7 +36,6 @@
  * @author Chris Povirk
  */
 @GwtCompatible
-@ElementTypesAreNonnullByDefault
 public abstract class ListIteratorTester<E extends @Nullable Object>
     extends AbstractIteratorTester<E, ListIterator<E>> {
   protected ListIteratorTester(

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

@@ -48,7 +48,6 @@
 // check the order if so.
 // TODO: Refactor to share code with SetTestBuilder etc.
 @GwtCompatible
-@ElementTypesAreNonnullByDefault
 public abstract class MapInterfaceTest<K extends @Nullable Object, V extends @Nullable Object>
     extends TestCase {
 

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

@@ -33,7 +33,6 @@
  * @author Kevin Bourrillion
  */
 @GwtCompatible
-@ElementTypesAreNonnullByDefault
 public class MinimalCollection<E extends @Nullable Object> extends AbstractCollection<E> {
   // TODO: expose allow nulls parameter?
 

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

@@ -34,7 +34,6 @@
  * @author Regina O'Dell
  */
 @GwtCompatible
-@ElementTypesAreNonnullByDefault
 public class MinimalSet<E extends @Nullable Object> extends MinimalCollection<E> implements Set<E> {
 
   @SuppressWarnings("unchecked") // empty Object[] as E[]

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

@@ -31,7 +31,6 @@
  * @author George van den Driessche
  */
 @GwtCompatible
-@ElementTypesAreNonnullByDefault
 public final class OneSizeGenerator<T, E extends @Nullable Object>
     implements OneSizeTestContainerGenerator<T, E> {
   private final TestContainerGenerator<T, E> generator;

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

@@ -32,7 +32,6 @@
  * @author George van den Driessche
  */
 @GwtCompatible
-@ElementTypesAreNonnullByDefault
 public interface OneSizeTestContainerGenerator<T, E extends @Nullable Object>
     extends TestSubjectGenerator<T>, TestContainerGenerator<T, E> {
   TestContainerGenerator<T, E> getInnerGenerator();

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

@@ -35,7 +35,6 @@
 
 /** Replacements for JUnit's {@code assertThrows} that work under GWT/J2CL. */
 @GwtCompatible(emulated = true)
-@ElementTypesAreNonnullByDefault
 final class ReflectionFreeAssertThrows {
   interface ThrowingRunnable {
     void run() throws Throwable;

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

@@ -31,7 +31,6 @@
  * @author Kevin Bourrillion
  */
 @GwtCompatible
-@ElementTypesAreNonnullByDefault
 public class SampleElements<E extends @Nullable Object> implements Iterable<E> {
   // TODO: rename e3, e4 => missing1, missing2
   private final E e0;

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

@@ -50,7 +50,6 @@
  * @since 33.4.0 (but since 21.0 in the JRE flavor)
  */
 @GwtCompatible
-@ElementTypesAreNonnullByDefault
 @SuppressWarnings("Java7ApiChecker")
 @IgnoreJRERequirement // Users will use this only if they're already using Spliterator.
 public final class SpliteratorTester<E extends @Nullable Object> {

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

@@ -27,7 +27,6 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-@ElementTypesAreNonnullByDefault
 public abstract class TestCharacterListGenerator implements TestListGenerator<Character> {
   @Override
   public SampleElements<Character> samples() {

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

@@ -26,6 +26,5 @@
  * @author Kevin Bourrillion
  */
 @GwtCompatible
-@ElementTypesAreNonnullByDefault
 public interface TestCollectionGenerator<E extends @Nullable Object>
     extends TestContainerGenerator<Collection<E>, E> {}

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

@@ -26,7 +26,6 @@
  * @author Kevin Bourrillion
  */
 @GwtCompatible
-@ElementTypesAreNonnullByDefault
 public abstract class TestCollidingSetGenerator implements TestSetGenerator<Object> {
   @Override
   public SampleElements<Object> samples() {

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

@@ -30,7 +30,6 @@
  * @author George van den Driessche
  */
 @GwtCompatible
-@ElementTypesAreNonnullByDefault
 public interface TestContainerGenerator<T, E extends @Nullable Object> {
   /** Returns the sample elements that this generate populates its container with. */
   SampleElements<E> samples();

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

@@ -30,7 +30,6 @@
  * @author Kevin Bourrillion
  */
 @GwtCompatible
-@ElementTypesAreNonnullByDefault
 public abstract class TestEnumMapGenerator implements TestMapGenerator<AnEnum, String> {
 
   @Override

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

@@ -29,7 +29,6 @@
  * @author Kevin Bourrillion
  */
 @GwtCompatible
-@ElementTypesAreNonnullByDefault
 public abstract class TestEnumSetGenerator implements TestSetGenerator<AnEnum> {
   @Override
   public SampleElements<AnEnum> samples() {

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

@@ -27,7 +27,6 @@
  * @author Gregory Kick
  */
 @GwtCompatible
-@ElementTypesAreNonnullByDefault
 public abstract class TestIntegerSetGenerator implements TestSetGenerator<Integer> {
   @Override
   public SampleElements<Integer> samples() {

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

@@ -29,7 +29,6 @@
  * @author Jared Levy
  */
 @GwtCompatible
-@ElementTypesAreNonnullByDefault
 public abstract class TestIntegerSortedSetGenerator extends TestIntegerSetGenerator {
   @Override
   protected abstract SortedSet<Integer> create(Integer[] elements);

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

@@ -26,7 +26,6 @@
  * @author Kevin Bourrillion
  */
 @GwtCompatible
-@ElementTypesAreNonnullByDefault
 public interface TestListGenerator<E extends @Nullable Object> extends TestCollectionGenerator<E> {
   @Override
   List<E> create(Object... elements);

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

@@ -31,7 +31,6 @@
  * @author Jesse Wilson
  */
 @GwtCompatible
-@ElementTypesAreNonnullByDefault
 public abstract class TestMapEntrySetGenerator<
         K extends @Nullable Object, V extends @Nullable Object>
     implements TestSetGenerator<Map.Entry<K, V>> {

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

@@ -26,7 +26,6 @@
  * @author George van den Driessche
  */
 @GwtCompatible
-@ElementTypesAreNonnullByDefault
 public interface TestMapGenerator<K extends @Nullable Object, V extends @Nullable Object>
     extends TestContainerGenerator<Map<K, V>, Map.Entry<K, V>> {
   K[] createKeyArray(int length);

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

@@ -26,7 +26,6 @@
  * @author Jared Levy
  */
 @GwtCompatible
-@ElementTypesAreNonnullByDefault
 public interface TestQueueGenerator<E extends @Nullable Object> extends TestCollectionGenerator<E> {
   @Override
   Queue<E> create(Object... elements);

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

@@ -26,7 +26,6 @@
  * @author Kevin Bourrillion
  */
 @GwtCompatible
-@ElementTypesAreNonnullByDefault
 public interface TestSetGenerator<E extends @Nullable Object> extends TestCollectionGenerator<E> {
   @Override
   Set<E> create(Object... elements);

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

@@ -27,7 +27,6 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-@ElementTypesAreNonnullByDefault
 public interface TestSortedMapGenerator<K extends @Nullable Object, V extends @Nullable Object>
     extends TestMapGenerator<K, V> {
   @Override

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

@@ -26,7 +26,6 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-@ElementTypesAreNonnullByDefault
 public interface TestSortedSetGenerator<E extends @Nullable Object> extends TestSetGenerator<E> {
   @Override
   SortedSet<E> create(Object... elements);

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

@@ -27,7 +27,6 @@
  * @author Jared Levy
  */
 @GwtCompatible
-@ElementTypesAreNonnullByDefault
 public abstract class TestStringCollectionGenerator implements TestCollectionGenerator<String> {
   @Override
   public SampleElements<String> samples() {

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

@@ -26,7 +26,6 @@
  * @author Kevin Bourrillion
  */
 @GwtCompatible
-@ElementTypesAreNonnullByDefault
 public abstract class TestStringListGenerator implements TestListGenerator<String> {
   @Override
   public SampleElements<String> samples() {

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

@@ -31,7 +31,6 @@
  * @author George van den Driessche
  */
 @GwtCompatible
-@ElementTypesAreNonnullByDefault
 public abstract class TestStringMapGenerator implements TestMapGenerator<String, String> {
 
   @Override

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

@@ -27,7 +27,6 @@
  * @author Jared Levy
  */
 @GwtCompatible
-@ElementTypesAreNonnullByDefault
 public abstract class TestStringQueueGenerator implements TestQueueGenerator<String> {
   @Override
   public SampleElements<String> samples() {

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

@@ -27,7 +27,6 @@
  * @author Kevin Bourrillion
  */
 @GwtCompatible
-@ElementTypesAreNonnullByDefault
 public abstract class TestStringSetGenerator implements TestSetGenerator<String> {
   @Override
   public SampleElements<String> samples() {

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

@@ -30,7 +30,6 @@
  * @author Chris Povirk
  */
 @GwtCompatible
-@ElementTypesAreNonnullByDefault
 public abstract class TestStringSortedMapGenerator extends TestStringMapGenerator
     implements TestSortedMapGenerator<String, String> {
   @Override

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

@@ -28,7 +28,6 @@
  * @author Jared Levy
  */
 @GwtCompatible
-@ElementTypesAreNonnullByDefault
 public abstract class TestStringSortedSetGenerator extends TestStringSetGenerator
     implements TestSortedSetGenerator<String> {
 

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

@@ -27,7 +27,6 @@
  * @author George van den Driessche
  */
 @GwtCompatible
-@ElementTypesAreNonnullByDefault
 public interface TestSubjectGenerator<T extends @Nullable Object> {
   T createTestSubject();
 }

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

@@ -27,7 +27,6 @@
  * @author Regina O'Dell
  */
 @GwtCompatible
-@ElementTypesAreNonnullByDefault
 public abstract class TestUnhashableCollectionGenerator<T extends Collection<UnhashableObject>>
     implements TestCollectionGenerator<UnhashableObject> {
   @Override

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

@@ -34,7 +34,6 @@
 @Ignore("test runners must not instantiate and run this directly, only via suites we build")
 // @Ignore affects the Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.
 @SuppressWarnings("JUnit4ClassUsedInJUnit3")
-@ElementTypesAreNonnullByDefault
 public abstract class AbstractBiMapTester<K extends @Nullable Object, V extends @Nullable Object>
     extends AbstractMapTester<K, V> {