NIFI-14869: Add MSSQL MERGE-based upsert via new DatabaseDialectService

[Adelwageeh96]

Implement supportsUpsert() and getUpsertStatement() in MSSQLDatabaseDialectService to produce a MERGE statement for UPSERT operations on SQL Server.

• Added new controller service: MSSQLDatabaseDialectService Provides SELECT with paging, UPSERT using MERGE, and basic ALTER/CREATE DDL generation for SQL Server 2012+.

• Added new controller service: MSSQL2008DatabaseDialectService Extends MSSQLDatabaseDialectService to support SQL Server 2008, including SELECT with ROW_NUMBER() paging.

• Registered both services in META-INF/services/org.apache.nifi.controller.ControllerService Enables NiFi to discover and use the new MSSQL dialect services.

• Added unit tests:

  • TestMSSQLDatabaseDialectService.java: Verifies SQL generation and UPSERT logic for MSSQLDatabaseDialectService.
  • TestMSSQL2008DatabaseDialectService.java: Verifies paging and SELECT logic for MSSQL2008DatabaseDialectService.

Summary

NIFI-14869

Tracking

Issue Tracking

• Apache NiFi Jira issue created

Pull Request Tracking

• Pull Request title starts with Apache NiFi Jira issue number: NIFI-14869
• Pull Request commit message starts with Apache NiFi Jira issue number: NIFI-14869

Pull Request Formatting

• Pull Request based on current revision of the main branch
• Pull Request refers to a feature branch with one commit containing changes

Verification

Build

• Build completed using ./mvnw clean install -P contrib-check
  • JDK 21

Licensing

• No new dependencies introduced

Documentation

• Documentation formatting appears as expected in rendered files

[github-actions]

Automated review is marking this PR as stale due to lack of updates in the past four months. This PR will be closed in 15 days if the stale label is not removed. This stale label and automated closure does not indicate a judgement of the PR, just lack of reviewer bandwidth and helps us keep the PR queue more manageable. If you would like this PR re-opened you can do so and a committer can remove the stale label. Or you can open a new PR. Try to help review other PRs to increase PR review bandwidth which in turn helps yours.

[exceptionfactory]

Thanks for working on this @Adelwageeh96, unfortunately available review cycles have not provided the opportunity to focus on considering this addition.

On a quick scan, I observed a handful of issues with the test implementation, including many unnecessary anonymous classes, instead of using standard implementations.

Since the original pull request submission, the project repository now requires signed commits, and has a handful of new Checkstyle rules.

I'm not sure if there will be available cycles to review these changes given the lack of activity. However, having this PR linked from the Jira issue provides a helpful point of reference if others are willing to review the changes.