SOLR-16218: Fix bug in in-place update when failOnVersionConflicts=false

[laminelam]

https://issues.apache.org/jira/browse/SOLR-16218

Description

Fix a bug in in-place update when failOnVersionConflicts=false.

When sending in-place/atomic updates for a non-existent doc with version=1 Solr throws 409 error even if failOnVersionConflicts is set to false.

Steps to Reproduce

• Send an update request (single or batch) that includes Update in-place/atomic command of a non-existent doc.
• Set Version=1
• Solr will throw 409 exception with "Document not found for update" message error.

Set failOnVersionConflicts=false

• Solr still throws the same error.

Expected

if failOnVersionConflicts=false Solr should ignore the error silently and continue processing the rest of the commands.

Actual Result

Solr throws 409 exception with "Document not found for update" message error.

Solution

Check in getUpdatedDocument if failOnVersionConflicts=true before throwing the exception.

Tests

Added test cases catching the expected behavior when _failOnVersionConflicts is set to true or false (default is true).

Checklist

Please review the following and check all that apply:

• I have reviewed the guidelines for How to Contribute and my code conforms to the standards described there to the best of my ability.
• I have created a Jira issue and added the issue ID to my pull request title.
• I have given Solr maintainers access to contribute to my PR branch. (optional but recommended)
• I have developed this patch against the main branch.
• I have run ./gradlew check.
• I have added tests for my changes.
• [] I have added documentation for the Reference Guide