@Override
  public boolean consistentWithEquals() {
    return keyCoder.consistentWithEquals() && valueCoder.consistentWithEquals();
  }
@Test
  public void testConsistentWithEquals() {
    MapCoder<Integer, Integer> coder = MapCoder.of(VarIntCoder.of(), VarIntCoder.of());
    assertTrue(coder.consistentWithEquals());
  }