feat: Implement evalFeatures() for optimized batch evaluation

lib/src/main/java/growthbook/sdk/java/GrowthBook.java

@@ -261,6 +261,23 @@ public <ValueType> FeatureResult<ValueType> evalFeature(String key, Class<ValueT
         return featureEvaluator.evaluateFeature(key, getEvaluationContext(), valueTypeClass);
     }
 
+    /**
+     * Evaluates a batch of features reusing a single {@link EvaluationContext}, so shared
+     * setup (attribute state, global context references) is not repeated per feature.
+     *
+     * @param featureKeys    the feature keys to evaluate
+     * @param valueTypeClass the expected value type (typically {@code Object.class} for mixed types)
+     * @param <ValueType>    the result value type
+     * @return a map from feature key to its {@link FeatureResult}
+     */
+    @Override
+    public <ValueType> Map<String, FeatureResult<ValueType>> evalFeatures(
+            List<String> featureKeys,
+            Class<ValueType> valueTypeClass
+    ) {
+        return featureEvaluator.evaluateFeatures(featureKeys, getEvaluationContext(), valueTypeClass);
+    }
+
     /**
      * Update the user's attributes
      *

lib/src/main/java/growthbook/sdk/java/IGrowthBook.java

@@ -6,6 +6,8 @@
 import growthbook.sdk.java.model.FeatureResult;
 import growthbook.sdk.java.stickyBucketing.StickyBucketService;
 import javax.annotation.Nullable;
+import java.util.List;
+import java.util.Map;
 
 interface IGrowthBook {
 
@@ -20,6 +22,16 @@ interface IGrowthBook {
 
     <ValueType> FeatureResult<ValueType> evalFeature(String key, Class<ValueType> valueTypeClass);
 
+    /**
+     * Evaluates a batch of features for the current user, reusing a single evaluation context.
+     *
+     * @param featureKeys    the feature keys to evaluate
+     * @param valueTypeClass the expected value type (typically {@code Object.class} for mixed types)
+     * @param <ValueType>    the result value type
+     * @return a map from feature key to its {@link FeatureResult}
+     */
+    <ValueType> Map<String, FeatureResult<ValueType>> evalFeatures(List<String> featureKeys, Class<ValueType> valueTypeClass);
+
     /**
      * Update the user's attributes
      *