// Setup
    File file = createTempFile();
    // Test
    assertThrows(
        IllegalArgumentException.class,
        () -> Files.map(file, MapMode.READ_WRITE, (long) Integer.MAX_VALUE + 1));
  }

  public void testGetFileExtension() {
    assertEquals("txt", Files.getFileExtension(".txt"));
    assertEquals("txt", Files.getFileExtension("blah.txt"));

    } finally {
      closer.close();
    }
  }

  private long countBySkipping(Reader reader) throws IOException {
    long count = 0;
    long read;
    while ((read = reader.skip(Long.MAX_VALUE)) != 0) {
      count += read;
    }
    return count;
  }

  /**
   * Appends the contents of this source to the given {@link Appendable} (such as a {@link Writer}).

    ZERO(0L, "0ms"),
    SMALL(SMALL_TIMEOUT_MILLIS, SMALL_TIMEOUT_MILLIS + "ms"),
    LARGE(UNEXPECTED_HANG_DELAY_MILLIS * 2, (2 * UNEXPECTED_HANG_DELAY_MILLIS) + "ms"),
    MAX(Long.MAX_VALUE, "+oo");

    final long millis;
    final String label;

    Timeout(long millis, String label) {
      this.millis = millis;
      this.label = label;
    }

    @Override

    ZERO(0L, "0ms"),
    SMALL(SMALL_TIMEOUT_MILLIS, SMALL_TIMEOUT_MILLIS + "ms"),
    LARGE(UNEXPECTED_HANG_DELAY_MILLIS * 2, (2 * UNEXPECTED_HANG_DELAY_MILLIS) + "ms"),
    MAX(Long.MAX_VALUE, "+oo");

    final long millis;
    final String label;

    Timeout(long millis, String label) {
      this.millis = millis;
      this.label = label;
    }

    @Override

 * and a fixed number of values. Each key must match the regex `[a-z0-9_-]{1,64}`. Values are byte
 * sequences, accessible as streams or files. Each value must be between `0` and `Int.MAX_VALUE`
 * bytes in length.
 *
 * The cache stores its data in a directory on the filesystem. This directory must be exclusive to
 * the cache; the cache may delete or overwrite files from its directory. It is an error for

     */
    private static final int UNSET_EXPECTED_SIZE = -1;

    private final Comparator<B> comparator;
    private int expectedSize = UNSET_EXPECTED_SIZE;
    private int maximumSize = Integer.MAX_VALUE;

    private Builder(Comparator<B> comparator) {
      this.comparator = checkNotNull(comparator);
    }

    /**

    val inFinished = false
    val flushHeaders: Boolean
    val stream: Http2Stream
    val streamId: Int

    writer.withLock {
      this.withLock {
        if (nextStreamId > Int.MAX_VALUE / 2) {
          shutdown(REFUSED_STREAM)
        }
        if (isShutdown) {
          throw ConnectionShutdownException()
        }
        streamId = nextStreamId
        nextStreamId += 2

  private final boolean omitEmptyStrings;
  private final Strategy strategy;
  private final int limit;

  private Splitter(Strategy strategy) {
    this(strategy, false, CharMatcher.none(), Integer.MAX_VALUE);
  }

  private Splitter(Strategy strategy, boolean omitEmptyStrings, CharMatcher trimmer, int limit) {
    this.strategy = strategy;
    this.omitEmptyStrings = omitEmptyStrings;
    this.trimmer = trimmer;

    }

    @Override
    public abstract Iterator<E> iterator();

    @Override
    public boolean remove(@CheckForNull Object o) {
      return multiset().remove(o, Integer.MAX_VALUE) > 0;
    }

    @Override
    public int size() {
      return multiset().entrySet().size();
    }
  }

  abstract static class EntrySet<E extends @Nullable Object>

    }

    @Override
    public abstract Iterator<E> iterator();

    @Override
    public boolean remove(@CheckForNull Object o) {
      return multiset().remove(o, Integer.MAX_VALUE) > 0;
    }

    @Override
    public int size() {
      return multiset().entrySet().size();
    }
  }

  abstract static class EntrySet<E extends @Nullable Object>