Implement copilot review comments

Author: esrakartalOpt

OptimizelySDK/Config/DatafileProjectConfig.cs

@@ -817,7 +817,9 @@ public bool IsFeatureExperiment(string experimentId)
         }
 
         /// <summary>
-        ///Returns the datafile corresponding to ProjectConfig
+        /// Gets or sets the region associated with the project configuration.
+        /// This typically indicates the data residency or deployment region (e.g., "us", "eu").
+        /// Valid values depend on the Optimizely environment and configuration.
         /// </summary>
         /// <returns>the datafile string corresponding to ProjectConfig</returns>
         public string ToDatafile()

OptimizelySDK/Event/Builder/EventBuilder.cs

@@ -242,9 +242,11 @@ public virtual LogEvent CreateImpressionEvent(ProjectConfig config, Experiment e
                 GetImpressionOrConversionParamsWithCommonParams(commonParams,
                     new object[] { impressionOnlyParams });
 
-            var region = !string.IsNullOrEmpty(config.Region) ? config.Region : "US";
+            var endpoint = EventFactory.EventEndpoints.ContainsKey(region)
+                ? EventFactory.EventEndpoints[region]
+                : EventFactory.EventEndpoints["US"];
 
-            return new LogEvent(EventFactory.EventEndpoints[region], impressionParams, HTTP_VERB, HTTP_HEADERS);
+            return new LogEvent(endpoint, impressionParams, HTTP_VERB, HTTP_HEADERS);
         }
 
 
@@ -270,9 +272,11 @@ public virtual LogEvent CreateConversionEvent(ProjectConfig config, string event
             var conversionParams =
                 GetImpressionOrConversionParamsWithCommonParams(commonParams, conversionOnlyParams);
 
-            var region = !string.IsNullOrEmpty(config.Region) ? config.Region : "US";
+            var endpoint = EventFactory.EventEndpoints.ContainsKey(region)
+                ? EventFactory.EventEndpoints[region]
+                : EventFactory.EventEndpoints["US"];
 
-            return new LogEvent(EventFactory.EventEndpoints[region], conversionParams, HTTP_VERB, HTTP_HEADERS);
+            return new LogEvent(endpoint, conversionParams, HTTP_VERB, HTTP_HEADERS);
         }
     }
 }