[FSSDK-11544] review update

Author: junaed-optimizely

OptimizelySDK.Tests/ProjectConfigTest.cs

@@ -1425,8 +1425,7 @@ public void TestGetHoldout_Integration()
             Assert.AreEqual("global_holdout", globalHoldout.Key);
 
             var invalidHoldout = datafileProjectConfig.GetHoldout("invalid_id");
-            Assert.IsNotNull(invalidHoldout);
-            Assert.AreEqual("", invalidHoldout.Id); // Dummy holdout has empty ID
+            Assert.IsNull(invalidHoldout);
         }
 
         [Test]
@@ -1461,8 +1460,7 @@ public void TestMissingHoldoutsField_BackwardCompatibility()
             Assert.AreEqual(0, holdouts.Length);
 
             var holdout = datafileProjectConfig.GetHoldout("any_id");
-            Assert.IsNotNull(holdout);
-            Assert.AreEqual("", holdout.Id); // Dummy holdout has empty ID
+            Assert.IsNull(holdout);
         }
 
         #endregion

OptimizelySDK/Config/DatafileProjectConfig.cs

@@ -795,7 +795,7 @@ public Rollout GetRolloutFromId(string rolloutId)
         /// Get the holdout from the ID
         /// </summary>
         /// <param name="holdoutId">ID for holdout</param>
-        /// <returns>Holdout Entity corresponding to the holdout ID or a dummy entity if ID is invalid</returns>
+        /// <returns>Holdout Entity corresponding to the holdout ID or null if ID is invalid</returns>
         public Holdout GetHoldout(string holdoutId)
         {
 #if NET35 || NET40
@@ -804,7 +804,7 @@ public Holdout GetHoldout(string holdoutId)
             if (string.IsNullOrWhiteSpace(holdoutId))
 #endif
             {
-                return new Holdout();
+                return null;
             }
 
             if (_HoldoutIdMap.ContainsKey(holdoutId))
@@ -816,7 +816,7 @@ public Holdout GetHoldout(string holdoutId)
             Logger.Log(LogLevel.ERROR, message);
             ErrorHandler.HandleError(
                 new InvalidExperimentException("Provided holdout is not in datafile."));
-            return new Holdout();
+            return null;
         }
 
         /// <summary>

OptimizelySDK/Entity/Holdout.cs

@@ -28,15 +28,6 @@ namespace OptimizelySDK.Entity
     /// </summary>
     public class Holdout : IdKeyEntity, IExperimentCore
     {
-        /// <summary>
-        /// Constructor that initializes properties to avoid null values
-        /// </summary>
-        public Holdout()
-        {
-            Id = "";
-            Key = "";
-        }
-
         /// <summary>
         /// Holdout status enumeration
         /// </summary>

OptimizelySDK/ProjectConfig.cs

@@ -322,7 +322,7 @@ public interface ProjectConfig
         /// Get the holdout from the ID
         /// </summary>
         /// <param name="holdoutId">ID for holdout</param>
-        /// <returns>Holdout Entity corresponding to the holdout ID or a dummy entity if ID is invalid</returns>
+        /// <returns>Holdout Entity corresponding to the holdout ID or null if ID is invalid</returns>
         Holdout GetHoldout(string holdoutId);
 
         /// <summary>

OptimizelySDK/Utils/HoldoutConfig.cs

@@ -120,17 +120,25 @@ public List<Holdout> GetHoldoutsForFlag(string flagId)
                 return _flagHoldoutCache[flagId];
 
             var activeHoldouts = new List<Holdout>();
-
             // Start with global holdouts, excluding any that are specifically excluded for this flag
             var excludedForFlag = _excludedHoldouts.ContainsKey(flagId) ? _excludedHoldouts[flagId] : new List<Holdout>();
 
-            foreach (var globalHoldout in _globalHoldouts)
+            if (excludedForFlag.Count > 0)
             {
-                if (!excludedForFlag.Contains(globalHoldout))
+                // Only iterate if we have exclusions to check
+                foreach (var globalHoldout in _globalHoldouts)
                 {
-                    activeHoldouts.Add(globalHoldout);
+                    if (!excludedForFlag.Contains(globalHoldout))
+                    {
+                        activeHoldouts.Add(globalHoldout);
+                    }
                 }
             }
+            else
+            {
+                // No exclusions, add all global holdouts directly
+                activeHoldouts.AddRange(_globalHoldouts);
+            }
 
             // Add included holdouts for this flag
             if (_includedHoldouts.ContainsKey(flagId))