fix: Property collision handling: ensure event properties take precedence over context properties

[Copilot]

When event properties and context properties share the same name, NLog's GetAllProperties allows context properties to overwrite event properties instead of renaming the duplicate. This causes the test EventPropertyKeyNameIsAppendedWith_1_IfSameAsGlobalDiagnosticContextKeyName to fail.

// Test setup: event property "Name" = "Value", context property "Name" renders to "Global Value"
eventInfo.Properties["Name"] = "Value";
target.ContextProperties.Add(new TargetPropertyWithContext("Name", "${gdc:item=Name}"));

// Expected: Name=Value, Name_1=Global Value
// Actual (before fix): Name=Global Value, Name_1=Global Value

Changes

• BuildPropertyBag: Manually collect properties instead of using GetAllProperties

  • Add event properties first (take precedence)
  • Add context properties second with duplicate detection
  • Helper method TryAddPropertyToPropertyBag appends _1, _2 suffixes for collisions

• Test: Remove [Ignore] attribute from previously failing test

This ensures event properties always retain their original names and values when collisions occur with context properties.

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Original prompt

---

This section details on the original issue you should resolve

<issue_title>Test EventPropertyKeyNameIsAppendedWith_1_IfSameAsGlobalDiagnosticContextKeyName fails</issue_title>
<issue_description>Currently, the test EventPropertyKeyNameIsAppendedWith_1_IfSameAsGlobalDiagnosticContextKeyName fails, because the properties "Name" and "Name_1" both contain the value "Global Value" instead of one of them being "Value". This might be due to how NLog processes properties internally. Check how other structured NLog targets work with the same configuration?

NLog.Targets.ApplicationInsights/test/NLogTarget.Tests/NLogTargetTests.cs

Lines 268 to 295 in 257f918

	[TestMethod]
	[Ignore("NLog behaviour seems to have changed, this test is no longer valid")]
	[TestCategory("NLogTarget")]
	#pragma warning disable CA1707 // Identifiers should not contain underscores
	public void EventPropertyKeyNameIsAppendedWith_1_IfSameAsGlobalDiagnosticContextKeyName()
	#pragma warning restore CA1707 // Identifiers should not contain underscores
	{
	using ApplicationInsightsTarget target = new()
	{
	IncludeGdc = true,
	IncludeEventProperties = true,
	IncludeScopeNested = true,
	IncludeScopeProperties = true
	};
	target.ContextProperties.Add(new TargetPropertyWithContext("Name", "${gdc:item=Name}"));
	var aiLogger = this.CreateTargetWithGivenConnectionString(target: target);
	GlobalDiagnosticsContext.Set("Name", "Global Value");
	var eventInfo = new LogEventInfo(LogLevel.Trace, "TestLogger", "Hello!");
	eventInfo.Properties["Name"] = "Value";
	aiLogger.Log(eventInfo);
	var telemetry = this.adapterHelper.Channel.SentItems.FirstOrDefault() as TraceTelemetry;
	Assert.IsTrue(telemetry.Properties.ContainsKey("Name"), "Key name altered");
	Assert.AreEqual("Value", telemetry.Properties["Name"]);
	Assert.IsTrue(telemetry.Properties.ContainsKey("Name_1"));
	Assert.AreEqual("Global Value", telemetry.Properties["Name_1"]);
	}

</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Test EventPropertyKeyNameIsAppendedWith_1_IfSameAsGlobalDiagnosticContextKeyName fails #10

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[codecov]

Codecov Report

❌ Patch coverage is 77.14286% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 60.80%. Comparing base (6d183c7) to head (c5bf928).
⚠️ Report is 9 commits behind head on dev.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
src/NLogTarget/ApplicationInsightsTarget.cs	77.14%	3 Missing and 5 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              dev      #75      +/-   ##
==========================================
- Coverage   62.76%   60.80%   -1.96%     
==========================================
  Files           3        3              
  Lines         239      273      +34     
  Branches       39       49      +10     
==========================================
+ Hits          150      166      +16     
- Misses         73       86      +13     
- Partials       16       21       +5     

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[github-actions]

🎉 This PR is included in version 1.2.0-beta.7 🎉

The release is available on:

• v1.2.0-beta.7
• GitHub release

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