import java.util.concurrent.TimeoutException;
import org.jspecify.annotations.Nullable;

/**
 * A {@link ListenableFuture} that supports fluent chains of operations. For example:
 *
 * {@snippet :
 * ListenableFuture<Boolean> adminIsLoggedIn =
 *     FluentFuture.from(usersDatabase.getAdminUser())
 *         .transform(User::getId, directExecutor())
 *         .transform(ActivityService::isLoggedIn, threadPool)

   * respective source streams. For example:
   *
   * {@snippet :
   * Streams.forEachPair(
   *   Stream.of("foo1", "foo2", "foo3"),
   *   Stream.of("bar1", "bar2"),
   *   (arg1, arg2) -> System.out.println(arg1 + ":" + arg2)
   * }
   *
   * <p>will print:
   *
   * {@snippet :
   * foo1:bar1
   * foo2:bar2
   * }
   *

 * whose next element can always be derived from the previous element. Null elements are not
 * supported, nor is the {@link #remove()} method.
 *
 * <p>Example:
 *
 * {@snippet :
 * Iterator<Integer> powersOfTwo =
 *     new AbstractSequentialIterator<Integer>(1) {
 *       protected Integer computeNext(Integer previous) {
 *         return (previous == 1 << 30) ? null : previous * 2;
 *       }

 * single-element enum to maintain serialization guarantees. See Effective Java (2nd Edition), Item
 * 3: "Enforce the singleton property with a private constructor or an enum type". For example:
 *
 * {@snippet :
 * public enum PersonFunnel implements Funnel<Person> {
 *   INSTANCE;
 *   public void funnel(Person person, PrimitiveSink into) {
 *     into.putUnencodedChars(person.getFirstName())

 * whose next element can always be derived from the previous element. Null elements are not
 * supported, nor is the {@link #remove()} method.
 *
 * <p>Example:
 *
 * {@snippet :
 * Iterator<Integer> powersOfTwo =
 *     new AbstractSequentialIterator<Integer>(1) {
 *       protected Integer computeNext(Integer previous) {
 *         return (previous == 1 << 30) ? null : previous * 2;
 *       }

import java.lang.reflect.Type;
import java.lang.reflect.TypeVariable;
import org.jspecify.annotations.Nullable;

/**
 * Captures a free type variable that can be used in {@link TypeToken#where}. For example:
 *
 * {@snippet :
 * static <T> TypeToken<List<T>> listOf(Class<T> elementType) {
 *   return new TypeToken<List<T>>() {}
 *       .where(new TypeParameter<T>() {}, elementType);
 * }
 * }
 *
 * @author Ben Yu
 * @since 12.0

 * times when the first style is more useful, use the multimap's {@link #asMap} view (or create a
 * {@code Map<K, Collection<V>>} in the first place).
 *
 * <h3>Example</h3>
 *
 * <p>The following code:
 *
 * {@snippet :
 * ListMultimap<String, String> multimap = ArrayListMultimap.create();
 * for (President pres : US_PRESIDENTS_IN_ORDER) {
 *   multimap.put(pres.firstName(), pres.lastName());
 * }

 * generally prefer the methods in {@link Comparator}; see <a href="#java8">below</a>.
 *
 * <p>Example usage of {@code ComparisonChain}:
 *
 * {@snippet :
 * public int compareTo(Foo that) {
 *   return ComparisonChain.start()
 *       .compare(this.aString, that.aString)
 *       .compare(this.anInt, that.anInt)

 * Tester to ensure forwarding wrapper works by delegating calls to the corresponding method with
 * the same parameters forwarded and return value forwarded back or exception propagated as is.
 *
 * <p>For example:
 *
 * {@snippet :
 * new ForwardingWrapperTester().testForwarding(Foo.class, new Function<Foo, Foo>() {
 *   public Foo apply(Foo foo) {
 *     return new ForwardingFoo(foo);
 *   }
 * });
 * }
 *
 * @author Ben Yu

   * java.util.stream} Javadoc), that order is preserved, but entries are <a
   * href="ImmutableMultimap.html#iteration">grouped by key</a>.
   *
   * <p>Example:
   *
   * {@snippet :
   * static final Multimap<Character, String> FIRST_LETTER_MULTIMAP =
   *     Stream.of("banana", "apple", "carrot", "asparagus", "cherry")