private abstract static class RawTypeConsistencyTester<T extends Enum<T> & CharSequence> {
    abstract T returningT();

    abstract void acceptT(T t);

    abstract <X extends T> X returningX();

    abstract <X> void acceptX(X x);

    abstract <T2 extends Enum<T2> & CharSequence> T2 returningT2();

    abstract <T2 extends CharSequence & Iterable<T2>> void acceptT2(T2 t2);

  private abstract static class RawTypeConsistencyTester<T extends Enum<T> & CharSequence> {
    abstract T returningT();

    abstract void acceptT(T t);

    abstract <X extends T> X returningX();

    abstract <X> void acceptX(X x);

    abstract <T2 extends Enum<T2> & CharSequence> T2 returningT2();

    abstract <T2 extends CharSequence & Iterable<T2>> void acceptT2(T2 t2);

              }
            },
            directExecutor()));
    thingToCancel[0] = serializer.submit(Callables.returning(null), directExecutor());
    results.add(thingToCancel[0]);
    // Enqueue more than enough tasks to force reentrancy.
    for (int i = 0; i < 5; i++) {
      results.add(serializer.submit(Callables.returning(null), directExecutor()));
    }

    manualExecutorTask[0].run();

public class CallablesTest extends TestCase {

  @J2ktIncompatible // TODO(b/324550390): Enable
  public void testReturning() throws Exception {
    assertNull(Callables.returning(null).call());

    Object value = new Object();
    Callable<Object> callable = Callables.returning(value);
    assertSame(value, callable.call());
    // Expect the same value on subsequent calls
    assertSame(value, callable.call());
  }

  @J2ktIncompatible

    assertFalse(task.isDone());
    task.run();
    assertTrue(task.isDone());
    assertFalse(task.isCancelled());
    assertEquals(2, getDone(task).intValue());
  }

  public void testCancelled() throws Exception {
    TrustedListenableFutureTask<Integer> task = TrustedListenableFutureTask.create(returning(2));
    assertFalse(task.isDone());
    task.cancel(false);

        });
    return holder.get();
  }

  /**
   * Updates the value currently associated with {@code key} by combining it with {@code x} via the
   * specified accumulator function, returning the new value. The previous value associated with
   * {@code key} (or zero, if there is none) is passed as the first argument to {@code
   * accumulatorFunction}, and {@code x} is passed as the second argument.
   *

        assertNotNull(provider1);
        assertNotNull(provider2);
        assertNotSame(provider1, provider2);
    }

    // Test with config returning null time adjustment
    public void test_nullTimeAdjustment() {
        FessConfig nullAdjustConfig = new FessConfig.SimpleImpl() {
            private static final long serialVersionUID = 1L;

            @Override

    } catch (UnsupportedOperationException e) {
      return;
    }

    Set<Entry<K, V>> entrySet = map.entrySet();
    if (supportsRemove) {
      try {
        entrySet.retainAll(null);
        // Returning successfully is not ideal, but tolerated.
      } catch (NullPointerException tolerated) {
      }
    } else {
      try {
        entrySet.retainAll(null);

   * next} field is lazily initialized. The type of that field would be {@code @Nullable T}, and the
   * code would be responsible for populating a "real" {@code T} (which might still be the value
   * {@code null}!) before returning it to callers. Depending on how the code is structured, a
   * nullness analysis might not understand that the field has been populated. To avoid that problem

    if (instance != null) {
      return (ListenableFuture<V>) instance;
    }
    return new ImmediateCancelledFuture<>();
  }

  /**
   * Executes {@code callable} on the specified {@code executor}, returning a {@code Future}.
   *
   * @throws RejectedExecutionException if the task cannot be scheduled for execution
   * @since 28.2
   */
  public static <O extends @Nullable Object> ListenableFuture<O> submit(