@Override
  public void write(byte[] b, int off, int len) throws IOException {
    out.write(b, off, len);
  }
@Test
  public void testWrite() throws IOException {
    CallCountOutputStream fsCount = new CallCountOutputStream();
    FilterOutputStream fs = new FilterOutputStream(fsCount);
    CallCountOutputStream osCount = new CallCountOutputStream();
    UnownedOutputStream os = new UnownedOutputStream(osCount);

    byte[] data = "Hello World!".getBytes(StandardCharsets.UTF_8);
    fs.write(data, 0, data.length);
    os.write(data, 0, data.length);
    fs.write('\n');
    os.write('\n');

    assertEquals(13, fsCount.callCnt);
    assertEquals(2, osCount.callCnt);
    assertArrayEquals(fsCount.toByteArray(), osCount.toByteArray());
  }