import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A {@link Future} which forwards all its method calls to another future. Subclasses should
 * override one or more methods to modify the behavior of the backing future as desired per the <a

  }

  /**
   * Returns a new {@code Future} whose result is asynchronously derived from the result of this
   * {@code Future}. If the input {@code Future} fails, the returned {@code Future} fails with the
   * same exception (and the function is not invoked).
   *
   * <p>More precisely, the returned {@code Future} takes its result from a {@code Future} produced

  @CanIgnoreReturnValue
  @ParametricNullness
  static <V extends @Nullable Object, X extends Exception> V getChecked(
      Future<V> future, Class<X> exceptionClass) throws X {
    return getChecked(bestGetCheckedTypeValidator(), future, exceptionClass);
  }

  /** Implementation of {@link Futures#getChecked(Future, Class)}. */
  @CanIgnoreReturnValue
  @VisibleForTesting
  @ParametricNullness

    final SettableFuture<@Nullable Void> future = SettableFuture.create();
    Object x =
        new Object() {
          @Override
          protected void finalize() {
            future.set(null);
          }
        };
    x = null; // Hint to the JIT that x is unreachable
    GcFinalization.awaitDone(future);
    assertTrue(future.isDone());
    assertFalse(future.isCancelled());
  }

	Go1_21 = "go1.21"
	Go1_22 = "go1.22"
)

// Future is an invalid unknown Go version sometime in the future.
// Do not use directly with Compare.
const Future = ""

// AtLeast reports whether the file version v comes after a Go release.
//
// Use this predicate to enable a behavior once a certain Go release
// has happened (and stays enabled in the future).
func AtLeast(v, release string) bool {
	if v == Future {

    checkNotNull(timeoutUnit);
    checkPositiveTimeout(timeoutDuration);

    Future<T> future = executor.submit(callable);

    try {
      return amInterruptible
          ? future.get(timeoutDuration, timeoutUnit)
          : getUninterruptibly(future, timeoutDuration, timeoutUnit);
    } catch (InterruptedException e) {
      future.cancel(true);
      throw e;
    } catch (ExecutionException e) {

 *       Future} is "completed" even if it is cancelled while its underlying work continues on a
 *       thread, an RPC, etc. The {@code Future} is also "completed" if it fails "early" -- for
 *       example, if the deadline expires on a {@code Future} returned from {@link
 *       Futures#withTimeout} while the {@code Future} it wraps continues its underlying work. So

      MockExecutor mock = new MockExecutor();
      TestExecutor testExecutor = new TestExecutor(mock);
      Future<?> f = testExecutor.submit(doNothing());
      mock.assertLastMethodCalled("submit");
      f.get();
    }
    {
      MockExecutor mock = new MockExecutor();
      TestExecutor testExecutor = new TestExecutor(mock);
      Future<String> f = testExecutor.submit(doNothing(), RESULT_VALUE);
      mock.assertLastMethodCalled("submit");

	OnComplete(cb func(try Try[T]), ctx ...Executor)
	IsCompleted() bool
	//	Value() Option[Try[T]]
	Failed() Future[error]
	Recover(f func(err error) T, ctx ...Executor) Future[T]
	RecoverWith(f func(err error) Future[T], ctx ...Executor) Future[T]
}

type Try[T any] struct {
	v   *T
	err error
}

func (r Try[T]) IsSuccess() bool {
	return r.v != nil
}

type ByteBuffer struct {
	pos       int
	buf       []byte

import java.util.concurrent.Executor;
import java.util.concurrent.Future;
import java.util.concurrent.RejectedExecutionException;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A {@link Future} that accepts completion listeners. Each listener has an associated executor, and
 * it is invoked using this executor once the future's computation is {@linkplain Future#isDone()