Validate reflective class names for connection properties

[Divang Sharma (divang)]

Description:
This change adds early validation for reflective class-name values supplied through connection properties such as socketFactoryClass and accessTokenCallbackClass. Malformed values are now rejected before reflective loading, which prevents confusing downstream failures and improves security posture.

What changed
Added validation in Util.newInstance to ensure the supplied value is a valid Java binary class name.
Added a dedicated driver error message for invalid reflective class names.
Added regression tests covering malformed socketFactoryClass and accessTokenCallbackClass values.

Why
Previously, malformed class-name values could reach reflective loading and fail later with less informative errors. This patch fails fast and makes the behavior explicit.

Validation
Verified with Maven compile
Verified with targeted regression tests: 2 tests run

[codecov]

Codecov Report

❌ Patch coverage is 90.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 60.23%. Comparing base (a45b6cb) to head (08e426f).

Files with missing lines	Patch %	Lines
...c/main/java/com/microsoft/sqlserver/jdbc/Util.java	90.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #3004      +/-   ##
============================================
+ Coverage     60.18%   60.23%   +0.05%     
- Complexity     5138     5164      +26     
============================================
  Files           153      153              
  Lines         36673    36679       +6     
  Branches       6733     6733              
============================================
+ Hits          22073    22095      +22     
- Misses        10751    10759       +8     
+ Partials       3849     3825      -24     

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[Copilot]

Pull request overview

Adds early validation for connection-property class names that are instantiated reflectively (e.g., socket factory and access token callback), failing fast on malformed values with a dedicated error message to avoid confusing reflective-loading failures.

Changes:

• Validate className in Util.newInstance using a Java identifier–based binary-name check before calling Class.forName.
• Introduce a new driver resource string (R_invalidClassNameForProperty) used when rejecting invalid class names.
• Add regression tests ensuring invalid reflective class-name payloads are rejected early for socketFactoryClass and accessTokenCallbackClass.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
src/main/java/com/microsoft/sqlserver/jdbc/Util.java	Adds pre-reflection class-name validation and new invalid-name error path.
src/main/java/com/microsoft/sqlserver/jdbc/SQLServerResource.java	Adds the localized error string for invalid reflective class-name values.
src/test/java/com/microsoft/sqlserver/jdbc/SQLServerConnectionTest.java	Adds tests asserting Util.newInstance rejects malformed class-name inputs.

[Muskan Gupta (muskan124947)]

testUtilNewInstanceRejectsInvalidSocketFactoryClassName and testUtilNewInstanceRejectsInvalidAccessTokenCallbackClassName are added to SQLServerConnectionTest, which extends AbstractTest and requires SQL Server test config — yet they only exercise Util.newInstance. They also duplicate the UtilTest parameterized coverage. Move them to UtilTest (no DB required) or delete them.