Allow setting index.creation_date on index creation for plugin compatibility and migrations

[AndreKurait]

Description

Allow setting index.creation_date on index creation for plugin compatibility and migrations.

Aligns behavior with snapshot restore to let migrations retain original creation timestamps.

Manual Testing

Verified with script which ran with output

➜  ~ ./validation.sh
=== CONFIG ===
Endpoint: http://localhost:9200
Suffix:   1762548057

=== 1) Create index WITHOUT explicit creation_date (test-index-auto-1762548057) ===
{
  "acknowledged": true,
  "shards_acknowledged": true,
  "index": "test-index-auto-1762548057"
}

--- GET settings (test-index-auto-1762548057) ---
{
  "test-index-auto-1762548057": {
    "settings": {
      "index": {
        "replication": {
          "type": "DOCUMENT"
        },
        "number_of_shards": "1",
        "provided_name": "test-index-auto-1762548057",
        "creation_date": "1762548057850",
        "number_of_replicas": "1",
        "uuid": "p9myRyg8S4SpIey0vMXIrw",
        "version": {
          "created": "137257827"
        }
      }
    }
  }
}
Requested: (auto-generated)
Actual:    1762548057850

=== 2) Create index WITH explicit creation_date (test-index-explicit-1762548057) ===
{
  "acknowledged": true,
  "shards_acknowledged": true,
  "index": "test-index-explicit-1762548057"
}

--- GET settings (test-index-explicit-1762548057) ---
{
  "test-index-explicit-1762548057": {
    "settings": {
      "index": {
        "replication": {
          "type": "DOCUMENT"
        },
        "number_of_shards": "1",
        "provided_name": "test-index-explicit-1762548057",
        "creation_date": "1234567890000",
        "number_of_replicas": "1",
        "uuid": "I3-vNRqLQz2xW4PKX3-Izw",
        "version": {
          "created": "137257827"
        }
      }
    }
  }
}
Requested: 1234567890000
Actual:    1234567890000

=== 3) Create INDEX TEMPLATE WITHOUT creation_date (no-date-template-1762548057) ===
{
  "acknowledged": true
}

--- GET template (no-date-template-1762548057) ---
{
  "index_templates": [
    {
      "name": "no-date-template-1762548057",
      "index_template": {
        "index_patterns": [
          "no-date-*1762548057"
        ],
        "template": {
          "settings": {
            "index": {
              "number_of_shards": "1"
            }
          }
        },
        "composed_of": []
      }
    }
  ]
}

--- Create index matching that template (no-date-1762548057) ---
{
  "acknowledged": true,
  "shards_acknowledged": true,
  "index": "no-date-1762548057"
}

--- GET settings (no-date-1762548057) ---
{
  "no-date-1762548057": {
    "settings": {
      "index": {
        "replication": {
          "type": "DOCUMENT"
        },
        "number_of_shards": "1",
        "provided_name": "no-date-1762548057",
        "creation_date": "1762548058741",
        "number_of_replicas": "1",
        "uuid": "LEAlsbeyQfSsCkAaV5sL7Q",
        "version": {
          "created": "137257827"
        }
      }
    }
  }
}
Requested: (auto-generated)
Actual:    1762548058741

=== 4) Create INDEX TEMPLATE WITH creation_date (with-date-template-1762548057) ===
{
  "acknowledged": true
}

--- GET template (with-date-template-1762548057) ---
{
  "index_templates": [
    {
      "name": "with-date-template-1762548057",
      "index_template": {
        "index_patterns": [
          "with-date-*1762548057"
        ],
        "template": {
          "settings": {
            "index": {
              "number_of_shards": "1",
              "creation_date": "1234567890000"
            }
          }
        },
        "composed_of": []
      }
    }
  ]
}

--- Create index matching that template (with-date-1762548057) ---
{
  "acknowledged": true,
  "shards_acknowledged": true,
  "index": "with-date-1762548057"
}

--- GET settings (with-date-1762548057) ---
{
  "with-date-1762548057": {
    "settings": {
      "index": {
        "replication": {
          "type": "DOCUMENT"
        },
        "number_of_shards": "1",
        "provided_name": "with-date-1762548057",
        "creation_date": "1234567890000",
        "number_of_replicas": "1",
        "uuid": "G_-aknqPSKaucpMWlK4QSw",
        "version": {
          "created": "137257827"
        }
      }
    }
  }
}
Requested: 1234567890000
Actual:    1234567890000

=== SUMMARY ===
Index                        | Source                 | Requested (ms)      | Actual (ms)         | Match
--------------------------------------------------------------------------------------------------------------
test-index-auto-1762548057   | direct (no date)       | (auto-generated)    | 1762548057850       | n/a  
test-index-explicit-1762548057 | direct (explicit date) | 1234567890000       | 1234567890000       | yes  
no-date-1762548057           | template (no date)     | (auto-generated)    | 1762548058741       | n/a  
with-date-1762548057         | template (explicit date) | 1234567890000       | 1234567890000       | yes  

Done.

Check List

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

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[peternied]

@AndreKurait Thanks for the PR, looks like you need to run ./gradlew spotlessApply and add a change log entry

[peternied]

@mch2 This seems like a pretty safe change that helps unblock migration scenarios with index state management, any concerns about taking this?

[AndreKurait]

@AndreKurait Thanks for the PR, looks like you need to run ./gradlew spotlessApply and add a change log entry

Updated spotless and added the changelog

[github-actions]

❌ Gradle check result for 07cb2b9: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?

[peternied]

@AndreKurait Looking at the failure - pretty sure it was impacted by this change, look into org.opensearch.client.IndicesClientIT.testCreateIndexFailPrivateSetting

[github-actions]

❌ Gradle check result for 07cb2b9: null

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?

[github-actions]

✅ Gradle check result for d23db8a: SUCCESS

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 73.18%. Comparing base (332efe3) to head (d23db8a).
⚠️ Report is 16 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #19931      +/-   ##
============================================
- Coverage     73.21%   73.18%   -0.04%     
- Complexity    71416    71553     +137     
============================================
  Files          5779     5785       +6     
  Lines        326332   326584     +252     
  Branches      47227    47291      +64     
============================================
+ Hits         238918   239001      +83     
- Misses        68189    68374     +185     
+ Partials      19225    19209      -16     

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[AndreKurait]

@peternied, I've addressed all tests failures and added new tests to verify behavior. I've updated the behavior to allow updating creation_date during restore of an index with snapshot_restore too

[peternied]

Thanks for the contribution @AndreKurait !