Change to track partition time breaks TimestampExtractor

Am testing the new version 2.3 for Kafka Streams specifically. I have noticed that now, the implementation of the method extract from the
interface org.apache.kafka.streams.processor.TimestampExtractor:

public class OwnTimeExtractor implements TimestampExtractor {

    @Override
    public long extract(final ConsumerRecord<Object, Object> record, final long previousTimestamp) {
        // previousTimestamp is always == -1. For version 2.3
    }
}

Previous version 2.2.1 was returning the correct value for the record partition.