private void writeObject(ObjectOutputStream outputStream) throws IOException {
		outputStream.writeObject(recordClazz);
		outputStream.writeObject(schemaString); // support for null
		outputStream.writeObject(retractKey);
		outputStream.writeObject(updateMode);
	}
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