KStreams :如何获取记录的(原始)主题？

import org.apache.kafka.streams.kstream.Transformer;
import org.apache.kafka.streams.processor.ProcessorContext;
import org.apache.kafka.streams.processor.PunctuationType;
import org.apache.kafka.streams.processor.Punctuator;
import org.apache.kafka.streams.processor.TimestampExtractor;

public class OriginalTopicTransformer implements Transformer<Key, Value, KeyValue<Key, Value>> {
    private ProcessorContext context;

    @Override
    public void init(ProcessorContext context) {
        this.context = context;
        // 定期调用 punctuate() 方法以获取记录的原始主题
        this.context.schedule(1000, PunctuationType.WALL_CLOCK_TIME, new Punctuator() {
            @Override
            public void punctuate(long timestamp) {
                KeyValue<Key, Value> record = (KeyValue<Key, Value>) context.currentRecord();
                String originalTopic = context.topic();
                // 在这里处理记录的原始主题
                // ...
            }
        });
    }

    @Override
    public KeyValue<Key, Value> transform(Key key, Value value) {
        // 在这里进行转换操作
        // ...
        return new KeyValue<>(key, value);
    }

    @Override
    public void close() {
        // 关闭资源
        // ...
    }
}