// TODO: test whether null is supported (create a Feature)
    /**
     * The elements to be returned by future calls to {@code next()}, with the first at the top of
     * the stack.
     */
    final Stack<E> nextElements = new Stack<>();

    /**
     * The elements to be returned by future calls to {@code previous()}, with the first at the top
     * of the stack.
     */

1. Fork the repository
2. Create a feature branch: `git checkout -b feature/amazing-feature`
3. Follow coding standards: `mvn formatter:format`
4. Add tests for new functionality
5. Ensure all tests pass: `mvn test`
6. Check license headers: `mvn license:format`
7. Commit changes: `git commit -m 'Add amazing feature'`
8. Push to branch: `git push origin feature/amazing-feature`
9. Open a Pull Request

### Code Style

  - name: Question or Problem
    about: Ask a question or ask about a problem in GitHub Discussions.
    url: https://github.com/fastapi/fastapi/discussions/categories/questions
  - name: Feature Request
    about: To suggest an idea or ask about a feature, please start with a question saying what you would like to achieve. There might be a way to do it already.
    url: https://github.com/fastapi/fastapi/discussions/categories/questions

import com.google.common.collect.testing.SetTestSuiteBuilder;
import com.google.common.collect.testing.TestSetGenerator;
import com.google.common.collect.testing.features.CollectionSize;
import com.google.common.collect.testing.features.Feature;
import java.util.Collections;
import java.util.EnumSet;
import java.util.List;
import java.util.Map.Entry;
import java.util.Set;
import junit.framework.TestSuite;

/**

support the alpha `scheduler.alpha.kubernetes.io/affinity` annotation on the Pod if you explicitly enable the alpha feature "AffinityInAnnotations", but it will be removed in a future release. When you upgrade to 1.6, if you have not enabled the alpha feature, then the scheduler will use the `affinity` field in PodSpec and will ignore the annotation. If you have enabled the alpha feature, then the scheduler will use the `affinity` field in PodSpec if it is present, and otherwise will use the annotation....

  }

  /**
   * Waits until the given future {@linkplain Future#isDone is done}, invoking the garbage collector
   * as necessary to try to ensure that this will happen.
   *
   * @throws RuntimeException if timed out or interrupted while waiting
   */
  @SuppressWarnings("removal") // b/260137033
  public static void awaitDone(Future<?> future) {
    if (future.isDone()) {
      return;
    }

      description: What type of issue would you like to report?
      multiple: false
      options:
        - Bug
        - Build/Install
        - Performance
        - Support
        - Feature Request
        - Documentation Feature Request
        - Documentation Bug
        - Others
    validations:
      required: true
  - type: markdown
    attributes:
      value: |

     * Future, then a call setException() would likely also overflow.
     *
     * - If the stack overflowed after set()/setValue() stored its result, then a call to
     * setException() will be a no-op because the Future is already done.
     *
     * Both scenarios are bad: The output Future might never complete, or, if it does complete, it

import com.google.common.util.concurrent.ListenableFuture;
import java.util.ArrayDeque;
import java.util.Deque;
import java.util.Map;
import java.util.concurrent.Executor;
import java.util.concurrent.Future;
import java.util.concurrent.atomic.AtomicInteger;
import junit.framework.TestCase;
import org.jspecify.annotations.NullUnmarked;

/**
 * Unit tests for {@link CacheLoader}.
 *
 * @author Charles Fry
 */

        this.featureSetName = featureSetName;
        return this;
    }

    /**
     * Gets the name of the feature store.
     *
     * @return The store name.
     */
    public String storeName() {
        return storeName;
    }

    /**
     * Sets the name of the feature store.
     *
     * @param storeName The store name.
     * @return This query builder.
     */