public short toShort() {
    int s = (mOwnerBits.ordinal() << 6) | (mGroupBits.ordinal() << 3) | mOtherBits.ordinal();
    return (short) s;
  }
@Test
  public void umask() {
    assertEquals(0700, ModeUtils.getUMask("0700").toShort());
    assertEquals(0755, ModeUtils.getUMask("0755").toShort());
    assertEquals(0644, ModeUtils.getUMask("0644").toShort());
  }