```kotlin
    if (credential == response.request.header("Authorization")) {
      return null // If we already failed with these credentials, don't retry.
     }
    ```

    You may also skip the retry when you’ve hit an application-defined attempt limit:

    /**
     * This returns true if the file's attributes contain any of the attributes
     * specified for this filter. The wildcard has no influence on this
     * method as the server should have performed that filtering already. The
     * attributes are asserted here only because server file systems may not
     * support filtering by all attributes (e.g. even though ATTR_DIRECTORY was

      return this;
    }

    /** Adds a key-value mapping to the built multimap if it is not already present. */
    @CanIgnoreReturnValue
    @Override
    public Builder<K, V> put(K key, V value) {
      super.put(key, value);
      return this;
    }

    /**
     * Adds an entry to the built multimap if it is not already present.
     *
     * @since 11.0
     */
    @CanIgnoreReturnValue
    @Override

     *     next
     * @since 33.4.0 (but since 28.0 in the JRE flavor)
     */
    @IgnoreJRERequirement // Users will use this only if they're already using Duration
    public static Scheduler newFixedDelaySchedule(Duration initialDelay, Duration delay) {
      return newFixedDelaySchedule(
          toNanosSaturated(initialDelay), toNanosSaturated(delay), NANOSECONDS);

**FastAPI** is all based on these type hints, they give it many advantages and benefits.

But even if you never use **FastAPI**, you would benefit from learning a bit about them.

/// note

If you are a Python expert, and you already know everything about type hints, skip to the next chapter.

///

## Motivation { #motivation }

Let's start with a simple example:

{* ../../docs_src/python_types/tutorial001.py *}

# We run this separately so that its change to the default toolchain doesn't affect anything else.
# (And we run it after the main build so that that build has already downloaded Java 11 if necessary.)
./mvnw --projects '!guava-testlib,!guava-tests,!guava-bom,!guava-gwt' initialize -P print-java-11-home
export JAVA_HOME=$(<target/java_11_home)

public interface RemovalListener<K, V> {
  /**
   * Notifies the listener that a removal occurred at some point in the past.
   *
   * <p>This does not always signify that the key is now absent from the cache, as it may have
   * already been re-added.
   */
  // Technically should accept RemovalNotification<? extends K, ? extends V>, but because
  // RemovalNotification is guaranteed covariant, let's make users' lives simpler.

  }

  // TODO(cpovirk): Use standard Javadoc form for SimpleForwarding* class and constructor
  /**
   * A simplified version of {@link ForwardingListenableFuture} where subclasses can pass in an
   * already constructed {@link ListenableFuture} as the delegate.
   *
   * @since 9.0
   */
  public abstract static class SimpleForwardingListenableFuture<V extends @Nullable Object>
      extends ForwardingListenableFuture<V> {

  fun request(): Request

  /**
   * Immediately and violently release resources held by this event source. This does nothing if
   * the event source has already been closed or canceled.
   */
  fun cancel()

  fun interface Factory {
    /**
     * Creates a new event source and immediately returns it. Creating an event source initiates an

import com.google.common.annotations.J2ktIncompatible;
import org.jspecify.annotations.Nullable;

/**
 * An {@link ImmutableAsList} implementation specialized for when the delegate collection is already
 * backed by an {@code ImmutableList} or array.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
@SuppressWarnings("serial") // uses writeReplace, not default serialization