message: Fix NPE on producing a message
diff: @@ -62,14 +62,12 @@ public class SchemaRegistryAwareRecordSerDe implements RecordSerDe {
  @Nullable
  private final JsonSchemaMessageFormatter jsonSchemaMessageFormatter;
  - private ObjectMapper objectMapper;
  + private final ObjectMapper objectMapper;
  - private SchemaRegistryClient createSchemaRegistryClient(KafkaCluster cluster,
  - ObjectMapper objectMapper) {
  + private SchemaRegistryClient createSchemaRegistryClient(KafkaCluster cluster) {
  if (cluster.getSchemaRegistry() == null) {
  throw new ValidationException("schemaRegistry is not specified");
  }
  - this.objectMapper = objectMapper;
  List<SchemaProvider> schemaProviders =
  List.of(new AvroSchemaProvider(), new ProtobufSchemaProvider(), new JsonSchemaProvider());
  @@ -98,8 +96,9 @@ public class SchemaRegistryAwareRecordSerDe implements RecordSerDe {
  public SchemaRegistryAwareRecordSerDe(KafkaCluster cluster, ObjectMapper objectMapper) {
  this.cluster = cluster;
  + this.objectMapper = objectMapper;
  this.schemaRegistryClient = cluster.getSchemaRegistry() != null
  - ? createSchemaRegistryClient(cluster, objectMapper)
  + ? createSchemaRegistryClient(cluster)
  : null;
  if (schemaRegistryClient != null) {
  this.avroFormatter = new AvroMessageFormatter(schemaRegistryClient);
  