@Override
    public ConsumerBuilder<T> deadLetterPolicy(DeadLetterPolicy deadLetterPolicy) {
        if (deadLetterPolicy != null) {
            checkArgument(deadLetterPolicy.getMaxRedeliverCount() > 0, "MaxRedeliverCount must be > 0.");
        }
        conf.setDeadLetterPolicy(deadLetterPolicy);
        return this;
    }
@Test
    public void testNullDeadLetterPolicy() {
        consumerBuilderImpl.deadLetterPolicy(null);
        verify(consumerBuilderImpl.getConf()).setDeadLetterPolicy(null);
    }