for (AtomicReader reader : mergeState.readers) {
final SegmentReader matchingSegmentReader = mergeState.matchingSegmentReaders[idx++];
CompressingStoredFieldsReader matchingFieldsReader = null;
if (matchingSegmentReader != null) {
final StoredFieldsReader fieldsReader = matchingSegmentReader.getFieldsReader();
// we can only bulk-copy if the matching reader is also a CompressingStoredFieldsReader
if (fieldsReader != null && fieldsReader instanceof CompressingStoredFieldsReader) {
matchingFieldsReader = (CompressingStoredFieldsReader) fieldsReader;
}
}