Unable to read index after MTAS upgrade

[reckart]

Lucene is able to work with indexes created with older versions of Lucene.

However, when upgrading MTAS say from 7.7.1.0 to 8.11.1.0, an exception is generated when trying to open the index:

2022-07-01 20:33:06 [main] ERROR MtasDocumentIndex - Unable to read MTAS index: codec mismatch: actual codec=Lucene70SegmentInfo vs expected codec=Lucene86SegmentInfo (resource=BufferedChecksumIndexInput(MMapIndexInput(path="/Users/bluefire/git/inception-application/inception/inception-search-mtas/target/test-output/MtasUpgradeTest/project/1/indexMtas/_0.si")))
org.apache.lucene.index.CorruptIndexException: codec mismatch: actual codec=Lucene70SegmentInfo vs expected codec=Lucene86SegmentInfo (resource=BufferedChecksumIndexInput(MMapIndexInput(path="/Users/bluefire/git/inception-application/inception/inception-search-mtas/target/test-output/MtasUpgradeTest/project/1/indexMtas/_0.si")))
	at org.apache.lucene.codecs.CodecUtil.checkHeaderNoMagic(CodecUtil.java:208) ~[lucene-core-8.11.1.jar:8.11.1 0b002b11819df70783e83ef36b42ed1223c14b50 - janhoy - 2021-12-14 13:46:43]
	at org.apache.lucene.codecs.CodecUtil.checkHeader(CodecUtil.java:198) ~[lucene-core-8.11.1.jar:8.11.1 0b002b11819df70783e83ef36b42ed1223c14b50 - janhoy - 2021-12-14 13:46:43]
	at org.apache.lucene.codecs.CodecUtil.checkIndexHeader(CodecUtil.java:255) ~[lucene-core-8.11.1.jar:8.11.1 0b002b11819df70783e83ef36b42ed1223c14b50 - janhoy - 2021-12-14 13:46:43]
	at org.apache.lucene.codecs.lucene86.Lucene86SegmentInfoFormat.read(Lucene86SegmentInfoFormat.java:95) ~[lucene-core-8.11.1.jar:8.11.1 0b002b11819df70783e83ef36b42ed1223c14b50 - janhoy - 2021-12-14 13:46:43]
	at org.apache.lucene.index.SegmentInfos.readCommit(SegmentInfos.java:357) ~[lucene-core-8.11.1.jar:8.11.1 0b002b11819df70783e83ef36b42ed1223c14b50 - janhoy - 2021-12-14 13:46:43]
	at org.apache.lucene.index.SegmentInfos.readCommit(SegmentInfos.java:291) ~[lucene-core-8.11.1.jar:8.11.1 0b002b11819df70783e83ef36b42ed1223c14b50 - janhoy - 2021-12-14 13:46:43]
	at org.apache.lucene.index.IndexWriter.<init>(IndexWriter.java:1037) ~[lucene-core-8.11.1.jar:8.11.1 0b002b11819df70783e83ef36b42ed1223c14b50 - janhoy - 2021-12-14 13:46:43]
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