protected AbstractIterator<FileChannelRecordBatch> batchIterator(int start) {
        final int end;
        if (isSlice)
            end = this.end;
        else
            end = this.sizeInBytes();
        FileLogInputStream inputStream = new FileLogInputStream(this, start, end);
        return new RecordBatchIterator<>(inputStream);
    }
Get an iterator over the record batches in the file, starting at a specific position. This is similar to
{@link #batches()} except that callers specify a particular position to start reading the batches from. This
method must be used with caution: the start position passed in must be a known start of a batch.
@param start The position to start record iteration from; must be a known position for start of a batch
@return An iterator over batches starting from {@code start}
clients/src/main/java/org/apache/kafka/common/record/FileRecords.java