DelegatingByTypeSerializer does not support null payload messages

[dimalesfar]

In what version(s) of Spring for Apache Kafka are you seeing this issue?
2.8.3

Describe the bug

DelegatingByTypeSerializer does not support null payload messages (Tombstone)

To Reproduce

@Bean
DefaultKafkaProducerFactoryCustomizer kafkaProducerFactoryCustomizer() {
    return producerFactory -> producerFactory.setValueSerializer((Serializer) new DelegatingByTypeSerializer (
            Map.of(
                   byte[].class, new ByteArraySerializer(),
                    AvroEvent.class, new KafkaAvroSerializer(),
                    XmlEvent.class, new CustumXmlSerializer())));
}

kafkaTemplate.send (key="abcd", value=null)

Expected behavior

Messages with value = null could be sent via KafkaTemplate

Actual behavior

Caused by: java.lang.NullPointerException: null
at org.springframework.kafka.support.serializer.DelegatingByTypeSerializer.findDelegate(DelegatingByTypeSerializer.java:114) ~[spring-kafka-2.8.3.jar:2.8.3]
at org.springframework.kafka.support.serializer.DelegatingByTypeSerializer.serialize(DelegatingByTypeSerializer.java:99) ~[spring-kafka-2.8.3.jar:2.8.3]
at org.apache.kafka.clients.producer.KafkaProducer.doSend(KafkaProducer.java:929) ~[kafka-clients-3.0.0.jar:na]
at org.apache.kafka.clients.producer.KafkaProducer.send(KafkaProducer.java:889) ~[kafka-clients-3.0.0.jar:na]
at org.springframework.kafka.core.DefaultKafkaProducerFactory$CloseSafeProducer.send(DefaultKafkaProducerFactory.java:993) ~[spring-kafka-2.8.3.jar:2.8.3]
at org.springframework.kafka.core.KafkaTemplate.doSend(KafkaTemplate.java:649) ~[spring-kafka-2.8.3.jar:2.8.3]
at org.springframework.kafka.core.KafkaTemplate.send(KafkaTemplate.java:429) ~[spring-kafka-2.8.

Workarround

public class CustomDelegatingByTypeSerializer extends DelegatingByTypeSerializer {

public CustomDelegatingByTypeSerializer(Map<Class<?>, Serializer> delegates) {
    super(delegates);
}

@Override
protected Serializer findDelegate(Object data, Map<Class<?>, Serializer> delegates) {
    if (data == null) {
        return new ByteArraySerializer();
    }
    return super.findDelegate(data, delegates);
}

}

Solution / proposition
All spring-kafka Serializer support messages with null values, this is why it's good if DelegatingByTypeSerializer can also handle it.

[garyrussell]

Thanks for reporting; duplicate of #2154

PR: #2160