* tasks would be called recursively. Here, we detect that the delegate executor is executing
   * inline, and maintain a queue to dispatch tasks iteratively. There is one instance of this class
   * per call to submit() or submitAsync(), and each instance supports only one call to execute().
   *
   * <p>This class would certainly be simpler and easier to reason about if it were built with

      Stopwatch s = Stopwatch.createStarted();
      // here is where you would do something
      total += s.elapsed(TimeUnit.NANOSECONDS);
    }
    return total;
  }

  @Benchmark
  long manual(int reps) {
    long total = 0;
    for (int i = 0; i < reps; i++) {
      long start = System.nanoTime();
      // here is where you would do something
      total += (System.nanoTime() - start);
    }

      Stopwatch s = Stopwatch.createStarted();
      // here is where you would do something
      total += s.elapsed(TimeUnit.NANOSECONDS);
    }
    return total;
  }

  @Benchmark
  long manual(int reps) {
    long total = 0;
    for (int i = 0; i < reps; i++) {
      long start = System.nanoTime();
      // here is where you would do something
      total += (System.nanoTime() - start);
    }

  @SuppressWarnings("unchecked")
  public static <T extends @Nullable Object> Collector<T, ?, T> onlyElement() {
    return (Collector) ONLY_ELEMENT;
  }

  /**
   * This atrocity is here to let us report several of the elements in the stream if there were more
   * than one, not just two.
   */
  private static final class ToOptionalState {
    static final int MAX_EXTRAS = 4;

    @CheckForNull Object element;
    List<Object> extras;

            return new Iterator<Integer>() {
              @Override
              public void remove() {
                // We should throw here, but we won't!
              }

              @Override
              public Integer next() {
                // We should throw here, but we won't!
                return 0;
              }

              @Override
              public boolean hasNext() {

  First came ten soldiers carrying clubs; these were all shaped
like the three gardeners, oblong and flat, with their hands and
feet at the corners:  next the ten courtiers; these were
ornamented all over with diamonds, and walked two and two, as the
soldiers did.  After these came the royal children; there were
ten of them, and the little dears came jumping merrily along hand
in hand, in couples:  they were all ornamented with hearts.  Next

  Logger get() {
    /*
     * We use double-checked locking. We could the try racy single-check idiom, but that would
     * depend on Logger not contain mutable state.
     *
     * We could use Suppliers.memoizingSupplier here, but I micro-optimized to this implementation
     * to avoid the extra class for the lambda (and maybe more for memoizingSupplier itself) and the
     * indirection.
     *

    return result;
  }

  /*
   * For discussion of the safety of the following methods for operating on predecessors and
   * successors, see the comments near the end of CompactHashMap, noting that the methods here call
   * requirePredecessors() and requireSuccessors(), which are defined at the end of this file.
   */

  private int getPredecessor(int entry) {
    return requirePredecessors()[entry] - 1;
  }

      @Override
      public int hashCode() {
        return 1;
      }
    }
  }

  private static void assertContains(String expectedSubstring, String actual) {
    // TODO(kevinb): use a Truth assertion here
    if (!actual.contains(expectedSubstring)) {
      fail("expected <" + actual + "> to contain <" + expectedSubstring + ">");
    }
  }

 * on TypeToken.where.) So, in the interest of failing fast and encouraging the user to switch to a
 * non-null bound if possible, let's require a non-null bound here.
 *
 * TODO(cpovirk): Elaborate on "wouldn't behave as users might expect."
 */
public abstract class TypeParameter<T> extends TypeCapture<T> {

  final TypeVariable<?> typeVariable;

  protected TypeParameter() {