@SuppressWarnings("unchecked")
	private void readObject(ObjectInputStream inputStream) throws ClassNotFoundException, IOException {
		recordClazz = (Class<? extends SpecificRecord>) inputStream.readObject();
		schemaString = (String) inputStream.readObject();
		if (recordClazz != null) {
			schema = SpecificData.get().getSchema(recordClazz);
		} else {
			schema = new Schema.Parser().parse(schemaString);
		}
		retractKey = (String) inputStream.readObject();
		updateMode = (String) inputStream.readObject();

		datumWriter = new SpecificDatumWriter<>(schema);
		arrayOutputStream = new ByteArrayOutputStream();
		encoder = EncoderFactory.get().binaryEncoder(arrayOutputStream, null);
	}
Creates an Avro serialization schema for the given Avro schema string.

@param avroSchemaString Avro schema string used to serialize Flink's row to Avro's record
kafka-base/kafka-base-sink/src/main/java/com/dtstack/flink/sql/sink/kafka/serialization/AvroTuple2SerializationSchema.java