@Override
    public int lastSequence() {
        int baseSequence = baseSequence();
        if (baseSequence == RecordBatch.NO_SEQUENCE)
            return RecordBatch.NO_SEQUENCE;
        return incrementSequence(baseSequence, lastOffsetDelta());
    }
Gets the base timestamp of the batch which is used to calculate the record timestamps from the deltas.

@return The base timestamp
clients/src/main/java/org/apache/kafka/common/record/DefaultRecordBatch.java