Comparable<Object> comparable = ArbitraryInstances.get(Comparable.class);
    assertEquals(0, comparable.compareTo(comparable));
    assertThat(comparable.compareTo("")).isGreaterThan(0);
    assertThrows(NullPointerException.class, () -> comparable.compareTo(null));
  }

  public void testGet_array() {
    assertThat(ArbitraryInstances.get(int[].class)).isEmpty();
    assertThat(ArbitraryInstances.get(Object[].class)).isEmpty();

   *   <li>All visible static methods are checked such that passing null for any parameter that's
   *       not annotated nullable (according to the rules of {@link NullPointerTester}) should throw
   *       {@link NullPointerException}.
   *   <li>If there is any visible constructor or visible static factory method declared by the
   *       class, all visible instance methods will be checked too using the instance created by

      entry.setValue(3);
      assertThat(cache.size()).isEqualTo(1);
      assertThat(cache.getIfPresent(1)).isEqualTo(3);
      checkValidState(cache);

      assertThrows(NullPointerException.class, () -> entry.setValue(null));
      checkValidState(cache);
    }
  }

  /* ---------------- Local utilities -------------- */

    @Override
    public OutputStream openStream() {
      return ByteStreams.nullOutputStream();
    }
  }

  // Compare by toString() to satisfy 2 properties:
  // 1. compareTo(null) should throw NullPointerException
  // 2. the order is deterministic and easy to understand, for debugging purpose.
  @SuppressWarnings("ComparableType")
  private static final class ByToString implements Comparable<Object>, Serializable {

    Comparable<Object> comparable = ArbitraryInstances.get(Comparable.class);
    assertEquals(0, comparable.compareTo(comparable));
    assertThat(comparable.compareTo("")).isGreaterThan(0);
    assertThrows(NullPointerException.class, () -> comparable.compareTo(null));
  }

  public void testGet_array() {
    assertThat(ArbitraryInstances.get(int[].class)).isEmpty();
    assertThat(ArbitraryInstances.get(Object[].class)).isEmpty();

    assertTrue(toTest, toTest.matches(expectedRegex));
  }

  public void testToString_addWithNullName() {
    MoreObjects.ToStringHelper helper = MoreObjects.toStringHelper(new TestClass());
    assertThrows(NullPointerException.class, () -> helper.add(null, "Hello"));
  }

  @GwtIncompatible // Class names are obfuscated in GWT
  public void testToString_addWithNullValue() {

   * We don't permit nulls, but we wrap every comparator with nullsFirst().
   * Why? We want for queries like containsKey(null) to return false, but the
   * GWT SortedMap implementation that we delegate to throws
   * NullPointerException if the comparator does. Since our construction
   * methods ensure that null is never present in the map, it's OK for the
   * comparator to look for it wherever it wants.
   *

 * converted to strings using {@link Object#toString()} before being appended.
 *
 * <p>If neither {@link #skipNulls()} nor {@link #useForNull(String)} is specified, the joining
 * methods will throw {@link NullPointerException} if any given element is null.
 *
 * <p><b>Warning: joiner instances are always immutable</b>; a configuration method such as {@code

        }
      }
    }
  }

  public void testToArray_withNull() {
    List<@Nullable Character> list = Arrays.asList((char) 0, (char) 1, null);
    assertThrows(NullPointerException.class, () -> Chars.toArray(list));
  }

  @J2ktIncompatible // b/285319375
  public void testAsList_isAView() {
    char[] array = {(char) 0, (char) 1};
    List<Character> list = Chars.asList(array);

 *  Fix: Don't close a `Deflater` while we're still using it to compress a web socket message. We
    had a severe bug where web sockets were closed on the wrong thread, which caused
    `NullPointerException` crashes in `Deflater`.

 *  Fix: Don't crash after a web socket fails its connection upgrade. We incorrectly released
    the web socket's connections back to the pool before their resources were cleaned up.