int initialSize = collection.size();
    assertTrue("remove(null) should return true", collection.remove(null));
    assertEquals(
        "remove(present) should decrease a collection's size by one.",
        initialSize - 1,
        collection.size());
    expectMissing((E) null);
  }

  @CollectionFeature.Require(absent = SUPPORTS_REMOVE)
  @CollectionSize.Require(absent = ZERO)

            getMap()
                .computeIfAbsent(
                    null,
                    k -> {
                      assertNull(k);
                      return v3();
                    }));
    expectUnchanged();
    expectNullKeyMissingWhenNullKeysUnsupported(
        "Should not contain null key after unsupported computeIfAbsent(null, function)");
  }

     * independently from <code>maven-toolchains-plugin</code>.
     *
     * @param session the Maven session, must not be {@code null}
     * @param type the type, must not be {@code null}
     * @param requirements the requirements, may be {@code null}
     * @return the matching toolchains, never {@code null}
     * @since 3.3.0
     */
    List<Toolchain> getToolchains(MavenSession session, String type, Map<String, String> requirements);

         */
        REP result,

        /**
         * Any error that occurred during processing; null if the request was successful
         */
        Throwable error) {

    /**
     * Determines if the request was processed successfully.
     *
     * @return true if no error occurred during processing (error is null), false otherwise
     */

    Map<C, V> row = safeGet(rowMap(), rowKey);
    return row != null && Maps.safeContainsKey(row, columnKey);
  }

  @Override
  public @Nullable V get(@Nullable Object rowKey, @Nullable Object columnKey) {
    Map<C, V> row = safeGet(rowMap(), rowKey);
    return (row == null) ? null : safeGet(row, columnKey);
  }

  @Override
  public boolean isEmpty() {
    return size() == 0;
  }

     *
     * @param key the key under which to store the session data, must not be {@code null}
     * @param oldValue the expected data currently associated with the key, may be {@code null}
     * @param newValue the data to associate with the key, may be {@code null} to remove the mapping
     * @return {@code true} if the key mapping was successfully updated from the old value to the new value,

  }

  public void testToString() {
    assertEquals("foo=1", entry("foo", 1).toString());
  }

  public void testToStringNull() {
    assertEquals("null=1", entry(NK, 1).toString());
    assertEquals("foo=null", entry("foo", NV).toString());
    assertEquals("null=null", entry(NK, NV).toString());
  }

  public void testEquals() {
    Entry<String, Integer> foo1 = entry("foo", 1);

        if (scopesToCollect == null) {
            scopesToCollect = Collections.emptySet();
        }
        if (scopesToResolve == null) {
            scopesToResolve = Collections.emptySet();
        }

        if (scopesToCollect.isEmpty() && scopesToResolve.isEmpty()) {
            return new SetWithResolutionResult(null, new LinkedHashSet<>());
        }

  @Throws(IOException::class)
  override fun authenticate(
    route: Route?,
    response: Response,
  ): Request? {
    if (route == null) throw NullPointerException("route == null")
    responses += response
    routes += route
    if (!schemeMatches(response) || credential == null) return null
    val header =
      when (response.code) {
        407 -> "Proxy-Authorization"
        else -> "Authorization"
      }

     */
    private Repository repository;

    /**
     * Creates a new exception with specified detail message and cause for the given repository.
     *
     * @param message The detail message, may be {@code null}.
     * @param repository The repository that caused the error, may be {@code null}.
     * @param cause The cause, may be {@code null}.
     */