/**
     * Gets the root directory of the session, which is the root directory for the top directory project.
     *
     * @return the root directory, never {@code null}
     * @throws IllegalStateException if the root directory could not be found
     * @see #getTopDirectory()
     * @see Project#getRootDirectory()
     * @see Project#isRootProject()
     */
    @Nonnull
    Path getRootDirectory();

    /**

   * If it contains {@link Double#NEGATIVE_INFINITY} and finite values only or {@link
   * Double#NEGATIVE_INFINITY} only, the result is {@link Double#NEGATIVE_INFINITY}.
   *
   * @throws IllegalStateException if the dataset is empty
   */
  public double mean() {
    checkState(count != 0);
    return mean;
  }

  /**
   * Returns the sum of the values.
   *
   * <h3>Non-finite values</h3>

    }

    public void test_constructor_withMessageAndCause() {
        // Test constructor with message and cause
        String message = "Command execution failed with error";
        Throwable cause = new IllegalStateException("Invalid state");
        CommandExecutionException exception = new CommandExecutionException(message, cause);

        assertNotNull(exception);
        assertEquals(message, exception.getMessage());

        // Test with cause only
        Exception cause = new IllegalStateException("Underlying error");
        DataStoreException exception = new DataStoreException(cause);

        assertNotNull(exception);
        assertEquals(cause, exception.getCause());
        assertEquals("java.lang.IllegalStateException: Underlying error", exception.getMessage());
        assertTrue(exception instanceof FessSystemException);

        // Test exception handling behavior
        try {
            throw new RuntimeCIFSException("Original message", new IllegalStateException("Cause"));
        } catch (RuntimeCIFSException e) {
            assertEquals("Original message", e.getMessage());
            assertTrue(e.getCause() instanceof IllegalStateException);
            assertEquals("Cause", e.getCause().getMessage());
        }
    }

    @Test

   *
   * <p>If {@code node} is removed from the network after this method is called, the {@code Set}
   * {@code view} returned by this method will be invalidated, and will throw {@code
   * IllegalStateException} if it is accessed in any way, with the following exceptions:
   *
   * <ul>
   *   <li>{@code view.equals(view)} evaluates to {@code true} (but any other {@code equals()}

          .put(ExecutionException.class, e -> e instanceof ExecutionException)
          .put(IllegalArgumentException.class, e -> e instanceof IllegalArgumentException)
          .put(IllegalStateException.class, e -> e instanceof IllegalStateException)
          .put(IndexOutOfBoundsException.class, e -> e instanceof IndexOutOfBoundsException)
          .put(NoSuchElementException.class, e -> e instanceof NoSuchElementException)

          .put(ExecutionException.class, e -> e instanceof ExecutionException)
          .put(IllegalArgumentException.class, e -> e instanceof IllegalArgumentException)
          .put(IllegalStateException.class, e -> e instanceof IllegalStateException)
          .put(IndexOutOfBoundsException.class, e -> e instanceof IndexOutOfBoundsException)
          .put(NoSuchElementException.class, e -> e instanceof NoSuchElementException)

    stopwatch.start();
    assertThrows(IllegalStateException.class, stopwatch::start);
    assertTrue(stopwatch.isRunning());
  }

  public void testStop() {
    stopwatch.start();
    assertSame(stopwatch, stopwatch.stop());
    assertFalse(stopwatch.isRunning());
  }

  public void testStop_new() {
    assertThrows(IllegalStateException.class, stopwatch::stop);
    assertFalse(stopwatch.isRunning());
  }

   * high wastes memory.
   *
   * @return this {@code CacheBuilder} instance (for chaining)
   * @throws IllegalArgumentException if {@code initialCapacity} is negative
   * @throws IllegalStateException if an initial capacity was already set
   */
  @CanIgnoreReturnValue
  public CacheBuilder<K, V> initialCapacity(int initialCapacity) {
    checkState(
        this.initialCapacity == UNSET_INT,