update to refactor buildAggregateMessage in ProviderError

Signed-off-by: Parth Suthar <parth.suthar@dynatrace.com>

Author: suthar26

src/main/java/dev/openfeature/sdk/multiprovider/FirstMatchStrategy.java

@@ -11,7 +11,6 @@
 import java.util.List;
 import java.util.Map;
 import java.util.function.Function;
-import java.util.stream.Collectors;
 import lombok.NoArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
 
@@ -65,19 +64,11 @@ public <T> ProviderEvaluation<T> evaluate(
         }
 
         // All providers either threw or returned FLAG_NOT_FOUND
-        String aggregateMessage = buildAggregateMessage(collectedErrors);
         return MultiProviderEvaluation.<T>multiProviderBuilder()
-                .errorMessage(aggregateMessage)
+                .errorMessage(
+                        ProviderError.buildAggregateMessage("Flag not found in any provider", collectedErrors))
                 .errorCode(FLAG_NOT_FOUND)
                 .providerErrors(collectedErrors)
                 .build();
     }
-
-    private static String buildAggregateMessage(List<ProviderError> errors) {
-        if (errors.isEmpty()) {
-            return "Flag not found in any provider";
-        }
-        String details = errors.stream().map(ProviderError::toString).collect(Collectors.joining(", "));
-        return "Flag not found in any provider. Provider errors: [" + details + "]";
-    }
 }

src/main/java/dev/openfeature/sdk/multiprovider/FirstSuccessfulStrategy.java

@@ -8,7 +8,6 @@
 import java.util.List;
 import java.util.Map;
 import java.util.function.Function;
-import java.util.stream.Collectors;
 import lombok.NoArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
 
@@ -50,19 +49,11 @@ public <T> ProviderEvaluation<T> evaluate(
             }
         }
 
-        String aggregateMessage = buildAggregateMessage(collectedErrors);
         return MultiProviderEvaluation.<T>multiProviderBuilder()
-                .errorMessage(aggregateMessage)
+                .errorMessage(
+                        ProviderError.buildAggregateMessage("No provider successfully responded", collectedErrors))
                 .errorCode(ErrorCode.GENERAL)
                 .providerErrors(collectedErrors)
                 .build();
     }
-
-    private static String buildAggregateMessage(List<ProviderError> errors) {
-        if (errors.isEmpty()) {
-            return "No provider successfully responded";
-        }
-        String details = errors.stream().map(ProviderError::toString).collect(Collectors.joining(", "));
-        return "No provider successfully responded. Provider errors: [" + details + "]";
-    }
 }

src/main/java/dev/openfeature/sdk/multiprovider/MultiProviderEvaluation.java

@@ -7,12 +7,13 @@
 import java.util.List;
 
 /**
- * A {@link ProviderEvaluation} subtype returned by multi-provider strategies when all providers
- * fail to produce a successful result.
+ * A {@link ProviderEvaluation} subtype returned by multi-provider strategies that carries
+ * per-provider error details.
  *
- * <p>This type carries per-provider error details so that callers can inspect why each individual
- * provider failed. It is only returned in error scenarios; successful evaluations always return
- * a plain {@link ProviderEvaluation}.
+ * <p>This type can represent both successful and failed evaluations. When a strategy exhausts
+ * all providers without a successful result, the per-provider errors describe why each provider
+ * failed. Custom strategies may also use this type for successful results to surface information
+ * about providers that were skipped or failed before the successful one.
  *
  * <p>Usage:
  * <pre>{@code
@@ -40,8 +41,9 @@ private MultiProviderEvaluation(
             ImmutableMetadata flagMetadata,
             List<ProviderError> providerErrors) {
         super(value, variant, reason, errorCode, errorMessage, flagMetadata);
-        this.providerErrors =
-                providerErrors != null ? Collections.unmodifiableList(providerErrors) : Collections.emptyList();
+        this.providerErrors = providerErrors != null
+                ? Collections.unmodifiableList(providerErrors)
+                : Collections.emptyList();
     }
 
     /**

src/main/java/dev/openfeature/sdk/multiprovider/ProviderError.java

@@ -2,6 +2,8 @@
 
 import dev.openfeature.sdk.ErrorCode;
 import dev.openfeature.sdk.exceptions.OpenFeatureError;
+import java.util.List;
+import java.util.stream.Collectors;
 import lombok.AllArgsConstructor;
 import lombok.Builder;
 import lombok.Data;
@@ -49,6 +51,20 @@ public static ProviderError fromException(String providerName, Exception excepti
         return new ProviderError(providerName, code, exception.getMessage(), exception);
     }
 
+    /**
+     * Build an aggregate error message from a list of provider errors.
+     *
+     * @param baseMessage the base message to use (e.g. "No provider successfully responded")
+     * @param errors      the list of per-provider errors
+     * @return an aggregate message including per-provider details
+     */
+    public static String buildAggregateMessage(String baseMessage, List<ProviderError> errors) {
+        String details = errors.stream()
+                .map(ProviderError::toString)
+                .collect(Collectors.joining(", "));
+        return baseMessage + ". Provider errors: [" + details + "]";
+    }
+
     @Override
     public String toString() {
         return providerName + ": " + errorCode + " (" + (errorMessage != null ? errorMessage : "unknown") + ")";