content: String? = null,
    fn: (FileDescriptor) -> T,
  ): T =
    assertOnPath(content) {
      FileInputStream(filePath.toFile()).use { fis ->
        fn(fis.fd)
      }
    }

  private inline fun <T> assertOnPath(
    content: String? = null,
    fn: (okio.Path) -> T,
  ): T {
    FileSystem.SYSTEM.write(filePath) {
      if (content != null) {
        writeUtf8(content)
      }

    initMultimapWithNullKey();

    assertContentsAnyOrder(multimap().removeAll(null), getValueForNullKey());

    expectMissing(mapEntry((K) null, getValueForNullKey()));
  }

  @MapFeature.Require({SUPPORTS_REMOVE, ALLOWS_ANY_NULL_QUERIES})
  public void testRemoveAllNullKeyAbsent() {
    assertEmpty(multimap().removeAll(null));
    expectUnchanged();
  }

     *
     * @param message The error message, may be {@code null}.
     * @param lineNumber The one-based index of the line containing the error or {@code -1} if unknown.
     * @param columnNumber The one-based index of the column containing the error or {@code -1} if unknown.
     * @param cause The nested cause of this error, may be {@code null}.
     */

        builder.startObject();
        if (sessionId != null) {
            builder.field(SESSION_ID, sessionId);
        }
        if (filterType != null) {
            builder.field(FILTER_TYPE, filterType);
        }
        if (url != null) {
            builder.field(URL, url);
        }
        builder.endObject();
        return builder;
    }

  static <T extends Throwable> T assertThrows(
      Class<T> expectedThrowable, ThrowingRunnable runnable) {
    return doAssertThrows(
        expectedThrowable,
        () -> {
          runnable.run();
          return null;
        },
        /* userPassedSupplier= */ false);
  }

  private static <T extends Throwable> T doAssertThrows(
      Class<T> expectedThrowable, ThrowingSupplier supplier, boolean userPassedSupplier) {

  static <T extends Throwable> T assertThrows(
      Class<T> expectedThrowable, ThrowingRunnable runnable) {
    return doAssertThrows(
        expectedThrowable,
        () -> {
          runnable.run();
          return null;
        },
        /* userPassedSupplier= */ false);
  }

  private static <T extends Throwable> T doAssertThrows(
      Class<T> expectedThrowable, ThrowingSupplier supplier, boolean userPassedSupplier) {

  static <T extends Throwable> T assertThrows(
      Class<T> expectedThrowable, ThrowingRunnable runnable) {
    return doAssertThrows(
        expectedThrowable,
        () -> {
          runnable.run();
          return null;
        },
        /* userPassedSupplier= */ false);
  }

  private static <T extends Throwable> T doAssertThrows(
      Class<T> expectedThrowable, ThrowingSupplier supplier, boolean userPassedSupplier) {

  static <T extends Throwable> T assertThrows(
      Class<T> expectedThrowable, ThrowingRunnable runnable) {
    return doAssertThrows(
        expectedThrowable,
        () -> {
          runnable.run();
          return null;
        },
        /* userPassedSupplier= */ false);
  }

  private static <T extends Throwable> T doAssertThrows(
      Class<T> expectedThrowable, ThrowingSupplier supplier, boolean userPassedSupplier) {

    }
    N previousNode = inEdgeMap.put(edge, node);
    checkState(previousNode == null);
  }

  @Override
  public void addOutEdge(E edge, N node) {
    checkNotNull(edge);
    checkNotNull(node);

    N previousNode = outEdgeMap.put(edge, node);
    checkState(previousNode == null);
  }

    Key(int value) {
      this.value = value;
    }

    @Override
    public synchronized String toString() {
      String s;
      if (toString != null) {
        s = toString.get();
        if (s != null) {
          return s;
        }
      }
      s = Integer.toString(value);
      toString = new WeakReference<>(s);
      return s;
    }
  }