Timestamp Configs for FlatPostgresCollection

[suddendust]

Config-Driven Timestamp Fields for Flat Collections

Summary

Adds auto-managed createdTime and lastUpdateTime fields for flat PostgreSQL collections, configurable via PostgresClient custom parameters.

Changes

• Config-driven timestamps: Timestamp column names specified via JSON config:

  customParams {
    timestampFields {
      "createdTsCol" : "createdTime",
      "lastUpdatedTsCol": "lastUpdateTime"}
    }
  }
  

• Type-aware conversion: Looks up column type from schema and converts appropriately (BIGINT → epoch millis, TIMESTAMPTZ → java.sql.Timestamp, etc.)
• Upsert behavior: createdTime preserved on updates, lastUpdateTime always updated
• Graceful degradation: Logs warning if config missing; no exception, columns remain NULL

Testing

• testTimestampsOnCreate - Validates both fields populated on create
• testTimestampsOnUpsert - Validates createdTime preserved, lastUpdateTime updated
• testNoExceptionWhenTimestampConfigMissing - Validates graceful handling when config absent

[codecov]

Codecov Report

❌ Patch coverage is 87.27273% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 80.71%. Comparing base (d112d17) to head (f68a964).

Files with missing lines	Patch %	Lines
...documentstore/postgres/FlatPostgresCollection.java	88.88%	1 Missing and 5 partials ⚠️
...core/documentstore/commons/FlatStoreConstants.java	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #274      +/-   ##
============================================
+ Coverage     80.65%   80.71%   +0.05%     
- Complexity     1396     1403       +7     
============================================
  Files           240      241       +1     
  Lines          6871     6926      +55     
  Branches        638      646       +8     
============================================
+ Hits           5542     5590      +48     
- Misses          914      916       +2     
- Partials        415      420       +5     

Flag	Coverage Δ
integration	80.71% <87.27%> (+0.05%)	⬆️
unit	53.08% <30.90%> (-0.18%)	⬇️

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[puneet-traceable]

This will be doable at what level? Per table ?