@SuppressWarnings("nullness") // safe because we pass sort() a range that contains real Ts
        T[] castBuffer = (T[]) buffer;
        // We've already taken O(k log k), let's make sure we don't take longer than O(k log k).
        Arrays.sort(castBuffer, left, right + 1, comparator);
        break;
      }
    }
    bufferSize = k;

    threshold = uncheckedCastNullableTToT(buffer[minThresholdPosition]);

    if (reference == null) {
      throw new VerifyException(lenientFormat(errorMessageTemplate, errorMessageArgs));
    }
    return reference;
  }

  // TODO(kevinb): consider <T> T verifySingleton(Iterable<T>) to take over for
  // Iterables.getOnlyElement()

  private Verify() {}

@GwtCompatible
@ElementTypesAreNonnullByDefault
/*
 * 1. The type parameter is <T> rather than <T extends @Nullable> so that we can use T in the
 * doForward and doBackward methods to indicate that the parameter cannot be null. (We also take
 * advantage of that for convertAll, as discussed on that method.)
 *
 * 2. The supertype of this class could be `Function<@Nullable A, @Nullable B>`, since

  protected static final boolean expensiveTests = Boolean.getBoolean("jsr166.expensiveTests");

  /**
   * If true, report on stdout all "slow" tests, that is, ones that take more than profileThreshold
   * milliseconds to execute.
   */
  private static final boolean profileTests = Boolean.getBoolean("jsr166.profileTests");

  /**

      else {
        nextIndex = takeIndex;
        nextItem = items[takeIndex];
      }
    }

    @Override
    public boolean hasNext() {
      /*
       * No sync. We can return true by mistake here
       * only if this iterator passed across threads,
       * which we don't support anyway.
       */
      return nextIndex >= 0;
    }

    /**

    }
  }

  /** Manages a {@link BlockingQueue} and associated timings for a {@code take} call. */
  private static final class TimedTakeQueue {
    final BlockingQueue<String> queue;
    final Completion completed;

    /**
     * Creates a {@link EnableReads} which insert an element for a {@code take} to receive in {@code
     * countdownInMillis}.
     */

        // TODO turn an equivalent back on when the RR plugin is released.

        /*

        This will not work until the RR plugin is released to get rid of the binding to the reporting exception which is a mistake.

        This happens after removing the reporting API from the core:

        java.lang.NoClassDefFoundError: org/apache/maven/reporting/MavenReportException

    int elements = Queues.drain(q, buf, -1, MAX_VALUE, NANOSECONDS);
    assertEquals(0, elements);
    assertThat(buf).isEmpty();

    // Free the producer thread, and give subsequent tests a clean slate.
    q.take();
  }

  public void testDrain_throws() throws Exception {
    for (BlockingQueue<Object> q : blockingQueues()) {
      testDrain_throws(q);
    }
  }

    ImmutableSet.Builder<ImmutableList<Class<?>>> allOverloads = ImmutableSet.builder();
    // The first two are for the overloads that don't take formatting args, e.g.
    // checkArgument(boolean) and checkArgument(boolean, Object)
    allOverloads.add(ImmutableList.<Class<?>>of(predicateType));
    allOverloads.add(ImmutableList.<Class<?>>of(predicateType, Object.class));

    }
  }

  /**
   * Returns {@code n} choose {@code k}, also known as the binomial coefficient of {@code n} and
   * {@code k}, that is, {@code n! / (k! (n - k)!)}.
   *
   * <p><b>Warning:</b> the result can take as much as <i>O(k log n)</i> space.
   *
   * @throws IllegalArgumentException if {@code n < 0}, {@code k < 0}, or {@code k > n}
   */
  public static BigInteger binomial(int n, int k) {
    checkNonNegative("n", n);