@Override
  public void clear() {
    mInternalMap.clear();
  }
@Test
  public void clear() {
    String x1 = new String("x");
    String x2 = new String("x");
    assertNull(mMap.put(x1, "z"));
    assertNull(mMap.put(x2, "z"));
    assertEquals(2, mMap.size());
    mMap.clear();
    assertEquals(0, mMap.size());
    assertEquals(0, mMap.keySet().size());
    assertEquals(0, mMap.entrySet().size());
  }