Remove the setShardIndex parameter in CollapseTopFieldDocs.merge()

[gaobinlong]

Description

In Lucene 9.0.0, this change was introduced that removes the ability of TopDocs.merge to set shard indices, and we adopted the change in 2.0.0, but CollapseTopFieldDocs.merge() still supports setting shard indices, that should also be removed.

As a result, when collapsing search results with concurrent segment search enabled, the shardIndex of the top docs are set twice in both queryPhase and FetchSearchPhase, that causes incorrect result are collected in queryPhase and later triggers an assertion error.

Actually, setting shard indices in queryPhase when calling CollapseTopFieldDocs.merge() is not needed because we are merging segment level results, they are all from one shard, we can only compare the lucene doc id when tie breaking for same sort value, small doc id wins.

This PR removes the setShardIndex parameter in CollapseTopFieldDocs.merge() method, following the change of the Lucene PR: apache/lucene-solr#757.

Related Issues

Resolves #19051 and #19111.

Check List

• Functionality includes testing.
  - [ ] API changes companion pull request created, if applicable.
  - [ ] Public documentation issue/PR created, if applicable.

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[github-actions]

❌ Gradle check result for 4d4d71f: FAILURE

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❌ Gradle check result for fb3b44d: FAILURE

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❌ Gradle check result for 65f8d3b: FAILURE

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[github-actions]

✅ Gradle check result for a803b86: SUCCESS

[codecov]

Codecov Report

❌ Patch coverage is 93.33333% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 72.83%. Comparing base (c442cce) to head (a803b86).
⚠️ Report is 25 commits behind head on main.

Files with missing lines	Patch %	Lines
...e/lucene/search/grouping/CollapseTopFieldDocs.java	92.30%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #19053      +/-   ##
============================================
- Coverage     72.98%   72.83%   -0.16%     
+ Complexity    69475    69436      -39     
============================================
  Files          5647     5647              
  Lines        319210   319206       -4     
  Branches      46171    46170       -1     
============================================
- Hits         232977   232493     -484     
- Misses        67385    67875     +490     
+ Partials      18848    18838      -10     

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[gaobinlong]

Hi @reta , mind taking a look at this PR? Thanks!

[reta]

Hi @reta , mind taking a look at this PR? Thanks!

Thanks @gaobinlong , LGTM, I just have one question / comment to understand what potential impact it could have, thank you.