private static final Predicate<@Nullable Integer> EVEN = input -> input == null || input % 2 == 0;
  static final Predicate<Entry<String, Integer>> CORRECT_LENGTH =
      input -> input.getKey().length() == input.getValue();

  abstract Map<String, Integer> createUnfiltered();

  public void testFilteredKeysIllegalPut() {
    Map<String, Integer> unfiltered = createUnfiltered();

  @Override
  protected void assertMoreInvariants(Map<K, V> map) {
    // TODO: can these be moved to MapInterfaceTest?
    for (Entry<K, V> entry : map.entrySet()) {
      assertEquals(entry.getKey() + "=" + entry.getValue(), entry.toString());
    }

    assertEquals("{" + JOINER.join(map.entrySet()) + "}", map.toString());
    assertEquals("[" + JOINER.join(map.entrySet()) + "]", map.entrySet().toString());

            final String hotThreads = response.getNodesMap().entrySet().stream().map(e -> {
                final StringBuilder tempBuf = new StringBuilder();
                append(tempBuf, StringEscapeUtils.escapeJson(e.getKey()), () -> StringEscapeUtils.escapeJson(e.getValue().getHotThreads()));
                return tempBuf.toString();
            }).collect(Collectors.joining(","));
            buf.append(hotThreads).append(',');

        // Act – serialise and parse back
        byte[] bytes = original.toByteArray();
        NegTokenTarg roundTrip = new NegTokenTarg(bytes);

        // Assert – all getters match the original values
        assertEquals(NegTokenTarg.ACCEPT_COMPLETED, roundTrip.getResult(), "result should roundtrip");
        assertEquals(mech, roundTrip.getMechanism(), "mechanism should roundtrip");

  @Override
  protected final void assertMoreInvariants(Map<K, V> map) {
    // TODO: can these be moved to MapInterfaceTest?
    for (Entry<K, V> entry : map.entrySet()) {
      assertEquals(entry.getKey() + "=" + entry.getValue(), entry.toString());
    }

    assertEquals("{" + JOINER.join(map.entrySet()) + "}", map.toString());
    assertEquals("[" + JOINER.join(map.entrySet()) + "]", map.entrySet().toString());

    for (RemovalNotification<String, String> notification : listener) {
      removalNotifications.put(notification.getKey(), notification.getValue());
      assertEquals(
          "Unexpected key/value pair passed to removalListener",
          notification.getKey(),
          notification.getValue());
    }

    // All of the seed values should have been visible, so we should have gotten removal

    for (RemovalNotification<String, String> notification : listener) {
      removalNotifications.put(notification.getKey(), notification.getValue());
      assertEquals(
          "Unexpected key/value pair passed to removalListener",
          notification.getKey(),
          notification.getValue());
    }

    // All of the seed values should have been visible, so we should have gotten removal

        // Verify that the object was created
        assertNotNull(pacString, "The PacUnicodeString object should not be null.");

        // Verify that the getters return the correct values
        assertEquals(length, pacString.getLength(), "The length should match the value provided in the constructor.");

  }

  private String expectedToString(Set<Entry<K, V>> entries) {
    Map<K, V> reference = new LinkedHashMap<>();
    for (Entry<K, V> entry : entries) {
      reference.put(entry.getKey(), entry.getValue());
    }
    return reference.toString();
  }

            return null;
        }
        String convertedUrl = url;
        for (final Map.Entry<String, String> entry : convertMap.entrySet()) {
            convertedUrl = convertedUrl.replaceAll(entry.getKey(), entry.getValue());
        }
        return convertedUrl;
    }

    /**
     * Adds a conversion rule.
     *
     * @param target The target string.
     * @param replacement The replacement string.