}
	if _, err := buf.Peek(1); err != io.EOF {
		t.Fatalf("want EOF got %v", err)
	}

	// Test for issue 3022, not exposing a reader's error on a successful Peek.
	buf = NewReaderSize(dataAndEOFReader("abcd"), 32)
	if s, err := buf.Peek(2); string(s) != "ab" || err != nil {
		t.Errorf(`Peek(2) on "abcd", EOF = %q, %v; want "ab", nil`, string(s), err)
	}
	if s, err := buf.Peek(4); string(s) != "abcd" || err != nil {

            stk.push(new ActivationFrame("arch", Optional.empty()));
            validator.accept(oa.getArch());
            stk.peek().location = "family";
            validator.accept(oa.getFamily());
            stk.peek().location = "name";
            validator.accept(oa.getName());
            stk.peek().location = "version";
            validator.accept(oa.getVersion());
            stk.pop();
            stk.pop();
        });

    Iterator<String> nonpeek = Lists.newArrayList("a", "b", "c").iterator();
    PeekingIterator<String> peek = peekingIterator(nonpeek);
    assertThat(nonpeek).isNotSameInstanceAs(peek);
    assertThat(peekingIterator(peek)).isSameInstanceAs(peek);
    assertThat(peekingIterator((Iterator<String>) peek)).isSameInstanceAs(peek);
  }

  public void testMergeSorted_stable_issue5773Example() {

   *     Iterators.peekingIterator(Iterators.forArray("a", "b"));
   * String a1 = peekingIterator.peek(); // returns "a"
   * String a2 = peekingIterator.peek(); // also returns "a"
   * String a3 = peekingIterator.next(); // also returns "a"
   * }
   *
   * <p>Any structural changes to the underlying iteration (aside from those performed by the
   * iterator's own {@link PeekingIterator#remove()} method) will leave the iterator in an undefined

   *     Iterators.peekingIterator(Iterators.forArray("a", "b"));
   * String a1 = peekingIterator.peek(); // returns "a"
   * String a2 = peekingIterator.peek(); // also returns "a"
   * String a3 = peekingIterator.next(); // also returns "a"
   * }
   *
   * <p>Any structural changes to the underlying iteration (aside from those performed by the
   * iterator's own {@link PeekingIterator#remove()} method) will leave the iterator in an undefined

    Iterator<String> nonpeek = Lists.newArrayList("a", "b", "c").iterator();
    PeekingIterator<String> peek = peekingIterator(nonpeek);
    assertThat(nonpeek).isNotSameInstanceAs(peek);
    assertThat(peekingIterator(peek)).isSameInstanceAs(peek);
    assertThat(peekingIterator((Iterator<String>) peek)).isSameInstanceAs(peek);
  }

  public void testMergeSorted_stable_issue5773Example() {

  fun dispatcherFromMockWebServer() {
    val dispatcher =
      object : okhttp3.mockwebserver.Dispatcher() {
        override fun dispatch(request: RecordedRequest): MockResponse = TODO()

        override fun peek(): MockResponse = TODO()

        override fun shutdown() = TODO()
      }
  }

  @Test
  fun dns() {
    var dns: Dns = Dns { TODO() }

    val system: Dns = Dns.SYSTEM
  }

                  } catch (ExecutionException expected) {
                  }
                  try {
                    peeker.getDone(nonInput);
                    fail("Peeker should not be able to peek into non-input ClosingFuture.");
                  } catch (IllegalArgumentException expected) {
                  }
                  capturedPeeker.set(peeker);
                  return closeable2;
                },

                  } catch (ExecutionException expected) {
                  }
                  try {
                    peeker.getDone(nonInput);
                    fail("Peeker should not be able to peek into non-input ClosingFuture.");
                  } catch (IllegalArgumentException expected) {
                  }
                  capturedPeeker.set(peeker);
                  return closeable2;
                },

    public boolean offer(E e) {
      synchronized (mutex) {
        return delegate().offer(e);
      }
    }

    @Override
    public @Nullable E peek() {
      synchronized (mutex) {
        return delegate().peek();
      }
    }

    @Override
    public @Nullable E poll() {
      synchronized (mutex) {
        return delegate().poll();
      }
    }