@Override
  public String toString() {
    checkNotNull(codecFactory, "Inner CodecFactory is null, please use non default constructor");
    return codecFactory.toString();
  }
@Test(expected = NullPointerException.class)
  public void testNullCodecToString() throws Exception {
    // use default CTR (available cause Serializable)
    SerializableAvroCodecFactory codec = new SerializableAvroCodecFactory();
    assertEquals("null", codec.toString());
  }