* already been determined.
   */
  public abstract <T extends @Nullable Object> ComparisonChain compare(
      @ParametricNullness T left, @ParametricNullness T right, Comparator<T> comparator);

  /**
   * Compares two {@code int} values as specified by {@link Ints#compare}, <i>if</i> the result of
   * this comparison chain has not already been determined.
   */

  }

  /**
   * Gets a {@code Throwable} cause chain as a list. The first entry in the list will be {@code
   * throwable} followed by its cause hierarchy. Note that this is a snapshot of the cause chain and
   * will not reflect any subsequent changes to the cause chain.
   *
   * <p>Here's an example of how it can be used to find specific types of exceptions in the cause
   * chain:
   *
   * <pre>

  }

  /**
   * Gets a {@code Throwable} cause chain as a list. The first entry in the list will be {@code
   * throwable} followed by its cause hierarchy. Note that this is a snapshot of the cause chain and
   * will not reflect any subsequent changes to the cause chain.
   *
   * <p>Here's an example of how it can be used to find specific types of exceptions in the cause
   * chain:
   *
   * <pre>

   */
  abstract void collectOneValue(int index, @ParametricNullness InputT returnValue);

  abstract void handleAllCompleted();

  /** Adds the chain to the seen set, and returns whether all the chain was new to us. */
  private static boolean addCausalChain(Set<Throwable> seen, Throwable param) {
    // Declare a "true" local variable so that the Checker Framework will infer nullness.

    /**
     * This method simply calls <tt>negotiate( req, resp, false )</tt>
     * and then <tt>chain.doFilter</tt>. You can override and call
     * negotiate manually to achive a variety of different behavior.
     */
    @Override
    public void doFilter ( ServletRequest request, ServletResponse response, FilterChain chain ) throws IOException, ServletException {
        HttpServletRequest req = (HttpServletRequest) request;

    firstException = expected;
    // Second time should also fail, with a cached causal chain.
    expected = assertThrows(PotentialDeadlockException.class, () -> lockA.lock());
    checkMessage(expected, "LockB -> LockA", "LockA -> LockB");
    // The causal chain should be cached.
    assertSame(firstException.getCause(), expected.getCause());
    // lockA should work after lockB is released.

   * part of the smeared hash of the element not covered by the hashtable mask, whereas the low bits
   * are the "next" pointer (pointing to the next entry in the bucket chain), which will always be
   * less than or equal to the hashtable mask.
   *
   * <pre>
   * hash  = aaaaaaaa
   * mask  = 00000fff
   * next  = 00000bbb
   * entry = aaaaabbb
   * </pre>
   *

          break;
        }
      }
    }
  }

  /**
   * Represents a detected cycle in lock acquisition ordering. The exception includes a causal chain
   * of {@code ExampleStackTrace} instances to illustrate the cycle, e.g.
   *
   * <pre>
   * com....PotentialDeadlockException: Potential Deadlock from LockC -&gt; ReadWriteA
   *   at ...
   *   at ...

      @Override
      boolean isCancelled() {
        return true;
      }

      @Override
      void maybeThrowOnGet(@Nullable Throwable cause) throws ExecutionException {
        // TODO(cpovirk): chain in a CancellationException created at the cancel() call?
        throw new CancellationException();
      }
    };

    boolean isDone() {
      return true;
    }

    boolean isCancelled() {

    InternalEntry<Object, Object, ?> entry = null;
    for (int i = 0; i < originalCount; i++) {
      Object key = new Object();
      Object value = new Object();
      int hash = map.hash(key);
      // chain all entries together as we only have a single bucket
      entry = segment.newEntryForTesting(key, hash, entry);
      segment.setValueForTesting(entry, value);
    }
    segment.setTableEntryForTesting(0, entry);