private void newFetchConfigFromConsumerConfig() {
        Properties p = new Properties();
        p.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092");
        p.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
        p.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
        ConsumerConfig config = new ConsumerConfig(p);
        new FetchConfig(config);
    }
Verify correctness if both the key and value {@link Deserializer deserializers} provided to the
{@link FetchConfig} constructors are {@code nonnull}.
clients/src/test/java/org/apache/kafka/clients/consumer/internals/FetchConfigTest.java