class NullabilityBreakingChangesRule extends AbstractGradleViolationRule {

    enum Nullability {
        NON_NULL, NULLABLE, UNMARKED,
    }

    private static final List<String> NULLABLE_ANNOTATIONS = [
        javax.annotation.Nullable,
        org.jetbrains.annotations.Nullable,
        org.jspecify.annotations.Nullable,
    ].collect { it.name }

                "Method com.example.Source.baz(java.lang.String): Return nullability changed from null-unmarked to non-nullable",
            )
            assertHasNoInformation()
        }
    }

    @Test
    fun `from null-unmarked returning to nullable returning is breaking`() {

        checkNotBinaryCompatibleJava(
            v1 = """

 */
package org.apache.maven.api.cli;

import java.util.List;

import org.apache.maven.api.annotations.Experimental;
import org.apache.maven.api.annotations.Nonnull;
import org.apache.maven.api.annotations.Nullable;

/**
 * Defines a simple logging interface for Maven CLI operations. These operations happen "early", when there may

  abstract <R> @Nullable R dummyReturnValue(TypeToken<R> returnType);

  private final class DummyHandler extends AbstractInvocationHandler implements Serializable {
    private final TypeToken<?> interfaceType;

    DummyHandler(TypeToken<?> interfaceType) {
      this.interfaceType = interfaceType;
    }

    @Override
    protected @Nullable Object handleInvocation(

     */
    public InvokerException(@Nullable String message) {
        super(message);
    }

    /**
     * Constructs a new {@code InvokerException} with the specified detail message and cause.
     *
     * @param message the detail message explaining the cause of the exception
     * @param cause the underlying cause of the exception
     */
    public InvokerException(@Nullable String message, @Nullable Throwable cause) {

   * equal to any other equality groups added to this tester.
   *
   * <p>The {@code @Nullable} annotations on the {@code equalityGroup} parameter imply that the
   * objects, and the array itself, can be null. That is for programmer convenience, when the
   * objects come from factory methods that are themselves {@code @Nullable}. In reality neither the
   * array nor its contents can be null, but it is not useful to force the use of {@code

 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.maven.cli.transfer;

import java.io.File;

import org.apache.maven.api.annotations.Nullable;
import org.eclipse.aether.transfer.TransferResource;

/**
 * Immutable identifier of a {@link TransferResource}.

  private static final class AlwaysEqual extends Ordering<@Nullable Object>
      implements Serializable {
    private static final AlwaysEqual INSTANCE = new AlwaysEqual();

    @Override
    @SuppressWarnings("UnusedVariable") // intentionally weird Comparator
    public int compare(@Nullable Object o1, @Nullable Object o2) {
      return 0;
    }

    @Override

import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/** Replacements for JUnit's {@code assertThrows} that work under GWT/J2CL. */
@GwtCompatible
@NullMarked
final class ReflectionFreeAssertThrows {
  interface ThrowingRunnable {
    void run() throws Throwable;
  }

  interface ThrowingSupplier {
    @Nullable Object get() throws Throwable;
  }

  @CanIgnoreReturnValue

package com.google.common.collect.testing;

import com.google.common.annotations.GwtCompatible;
import java.util.Collections;
import java.util.Iterator;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/**
 * A utility for testing an Iterator implementation by comparing its behavior to that of a "known
 * good" reference implementation. In order to accomplish this, it's important to test a great