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feat: Allow for providers with equal name in the multiprovider #1848

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84e9870
Allow for providers with equal name in the multiprovider
Feb 10, 2026
d5e3b1e
fixup: immutable list, add api changes
toddbaert Jul 30, 2026
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8 changes: 3 additions & 5 deletions src/main/java/dev/openfeature/sdk/multiprovider/FirstMatchStrategy.java
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Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,6 @@
import dev.openfeature.sdk.exceptions.FlagNotFoundError;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.function.Function;
import lombok.NoArgsConstructor;
import lombok.extern.slf4j.Slf4j;
Expand All @@ -34,16 +33,15 @@ public class FirstMatchStrategy implements Strategy {

@Override
public <T> ProviderEvaluation<T> evaluate(
Map<String, FeatureProvider> providers,
List<FeatureProvider> providers,
String key,
T defaultValue,
EvaluationContext ctx,
Function<FeatureProvider, ProviderEvaluation<T>> providerFunction) {
List<ProviderError> collectedErrors = new ArrayList<>();

for (Map.Entry<String, FeatureProvider> entry : providers.entrySet()) {
String providerName = entry.getKey();
FeatureProvider provider = entry.getValue();
for (FeatureProvider provider : providers) {
String providerName = provider.getMetadata().getName();
try {
ProviderEvaluation<T> res = providerFunction.apply(provider);
ErrorCode errorCode = res.getErrorCode();
Expand Down
8 changes: 3 additions & 5 deletions src/main/java/dev/openfeature/sdk/multiprovider/FirstSuccessfulStrategy.java
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Expand Up @@ -6,7 +6,6 @@
import dev.openfeature.sdk.ProviderEvaluation;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.function.Function;
import lombok.NoArgsConstructor;
import lombok.extern.slf4j.Slf4j;
Expand All @@ -25,16 +24,15 @@ public class FirstSuccessfulStrategy implements Strategy {

@Override
public <T> ProviderEvaluation<T> evaluate(
Map<String, FeatureProvider> providers,
List<FeatureProvider> providers,
String key,
T defaultValue,
EvaluationContext ctx,
Function<FeatureProvider, ProviderEvaluation<T>> providerFunction) {
List<ProviderError> collectedErrors = new ArrayList<>();

for (Map.Entry<String, FeatureProvider> entry : providers.entrySet()) {
String providerName = entry.getKey();
FeatureProvider provider = entry.getValue();
for (FeatureProvider provider : providers) {
String providerName = provider.getMetadata().getName();
try {
ProviderEvaluation<T> res = providerFunction.apply(provider);
if (res.getErrorCode() == null) {
Expand Down
36 changes: 10 additions & 26 deletions src/main/java/dev/openfeature/sdk/multiprovider/MultiProvider.java
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Original file line number Diff line number Diff line change
Expand Up @@ -10,13 +10,9 @@
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import lombok.Getter;
Expand All @@ -38,7 +34,7 @@ public class MultiProvider extends EventProvider {
// Use CPU count as upper bound for init threads.
public static final int INIT_THREADS_COUNT = Runtime.getRuntime().availableProcessors();

private final Map<String, FeatureProvider> providers;
private final List<FeatureProvider> providers;
private final Strategy strategy;
private MultiProviderMetadata metadata;

Expand All @@ -59,22 +55,10 @@ public MultiProvider(List<FeatureProvider> providers) {
* @param strategy the strategy (if {@code null}, {@link FirstMatchStrategy} is used)
*/
public MultiProvider(List<FeatureProvider> providers, Strategy strategy) {
this.providers = buildProviders(providers);
this.providers = providers;
this.strategy = Objects.requireNonNull(strategy, "strategy must not be null");
}

@coderabbitai coderabbitai Bot Jul 30, 2026

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🗄️ Data Integrity & Integration | 🟠 Major | ⚡ Quick win

🧩 Analysis chain

🏁 Script executed:

#!/bin/bash
set -euo pipefail

echo "== candidate files =="
fd -a 'MultiProvider\.java|.*Provider.*\.java' . | sed 's#^\./##' | head -50

echo "== MultiProvider outline and relevant source =="
if [ -f src/main/java/dev/openfeature/sdk/multiprovider/MultiProvider.java ]; then
  wc -l src/main/java/dev/openfeature/sdk/multiprovider/MultiProvider.java
  ast-grep outline src/main/java/dev/openfeature/sdk/multiprovider/MultiProvider.java || true
  cat -n src/main/java/dev/openfeature/sdk/multiprovider/MultiProvider.java
else
  echo "MultiProvider.java not found at expected path"
fi

echo "== usages / references =="
rg -n "MultiProvider|providers|strategy" src/main/java/dev/openfeature/sdk -S || true

echo "== behavioral probe: direct retention and mutation impact =="
python3 - <<'PY'
import re, pathlib
p = pathlib.Path('src/main/java/dev/openfeature/sdk/multiprovider/MultiProvider.java')
s = p.read_text()
checks = {
  "constructor_stores_providers_directly": "this.providers = providers" in s,
  "initializes_unmodifiable_metadata": "unmodifiableList" in s and "providerMetadata" in s,
  "passes_providers_to_strategy": bool(re.search(r'strategy\s*=\s*.*provider.*\)', s, re.S)) or 'providers' in s and 'strategy' in s,
}
print(checks)
# Minimal Java-ish simulation of retaining a caller's mutable list and later mutation.
providers = ["A", "B"]
metadata = [f"{p}/meta" for p in providers]
providers.append("C")
print(metadata)
try:
    for p in providers:
        print(p)
        providers.remove("B")
except RuntimeError as e:
    print("mutation_while_iterating_error_type=", type(e).__name__)
PY

Repository: open-feature/java-sdk

Length of output: 22557

Snapshot the provider list in the constructor.

MultiProvider retains the caller-supplied mutable list and passes it to strategies during evaluations. If callers mutate the list later, initialization results can diverge from lifecycle operations or evaluation behavior, and concurrent iteration can fail. Preserve duplicates and order while storing an unmodifiable defensive copy.

Proposed fix 
-        this.providers = providers;
+        this.providers = Collections.unmodifiableList(
+                new ArrayList<>(Objects.requireNonNull(providers, "providers must not be null")));
📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
this.providers = providers;
this.strategy = Objects.requireNonNull(strategy, "strategy must not be null");
}
this.providers = Collections.unmodifiableList(
new ArrayList<>(Objects.requireNonNull(providers, "providers must not be null")));
this.strategy = Objects.requireNonNull(strategy, "strategy must not be null");
}
🤖 Prompt for AI Agents 
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@src/main/java/dev/openfeature/sdk/multiprovider/MultiProvider.java` around
lines 58 - 60, Update the MultiProvider constructor to store an unmodifiable
defensive copy of the supplied providers list rather than retaining the caller’s
mutable list. Preserve the list’s original order and duplicate entries, and keep
strategy initialization, lifecycle operations, and evaluations using this stable
snapshot.


protected static Map<String, FeatureProvider> buildProviders(List<FeatureProvider> providers) {
Map<String, FeatureProvider> providersMap = new LinkedHashMap<>(providers.size());
for (FeatureProvider provider : providers) {
FeatureProvider prevProvider =
providersMap.put(provider.getMetadata().getName(), provider);
if (prevProvider != null) {
log.info("duplicated provider name: {}", provider.getMetadata().getName());
}
}
return Collections.unmodifiableMap(providersMap);
}

/**
* {@inheritDoc}
*
Expand All @@ -95,27 +79,27 @@ public void initialize(EvaluationContext evaluationContext) throws Exception {
@Override
public void initialize(EvaluationContext evaluationContext, String domain) throws Exception {
var metadataBuilder = MultiProviderMetadata.builder().name(NAME);
HashMap<String, Metadata> providersMetadata = new HashMap<>();

if (providers.isEmpty()) {
metadataBuilder.originalMetadata(Collections.unmodifiableMap(providersMetadata));
metadataBuilder.originalMetadata(Collections.emptyList());
metadata = metadataBuilder.build();
return;
}

ExecutorService executorService = Executors.newFixedThreadPool(Math.min(INIT_THREADS_COUNT, providers.size()));
List<Metadata> providersMetadata = new ArrayList<>(providers.size());

var executorService = Executors.newFixedThreadPool(Math.min(INIT_THREADS_COUNT, providers.size()));
try {
Collection<Callable<Void>> tasks = new ArrayList<>(providers.size());
for (FeatureProvider provider : providers.values()) {
for (FeatureProvider provider : providers) {
tasks.add(() -> {
provider.initialize(evaluationContext, domain);
return null;
});
Metadata providerMetadata = provider.getMetadata();
providersMetadata.put(providerMetadata.getName(), providerMetadata);
providersMetadata.add(provider.getMetadata());
}

metadataBuilder.originalMetadata(Collections.unmodifiableMap(providersMetadata));
metadataBuilder.originalMetadata(Collections.unmodifiableList(providersMetadata));

List<Future<Void>> results = executorService.invokeAll(tasks);
for (Future<Void> result : results) {
Expand Down Expand Up @@ -175,7 +159,7 @@ public ProviderEvaluation<Value> getObjectEvaluation(String key, Value defaultVa
@Override
public void shutdown() {
log.debug("shutdown begin");
for (FeatureProvider provider : providers.values()) {
for (FeatureProvider provider : providers) {
try {
provider.shutdown();
} catch (Exception e) {
Expand Down
6 changes: 3 additions & 3 deletions src/main/java/dev/openfeature/sdk/multiprovider/MultiProviderMetadata.java
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@@ -1,20 +1,20 @@
package dev.openfeature.sdk.multiprovider;

import dev.openfeature.sdk.Metadata;
import java.util.Map;
import java.util.List;
import lombok.Builder;
import lombok.Value;

/**
* Metadata for {@link MultiProvider}.
*
* <p>Contains the multiprovider's own name and a map of the original metadata from each underlying
* <p>Contains the multiprovider's own name and a list of the original metadata from each underlying
* provider.
*/
@Value
@Builder
public class MultiProviderMetadata implements Metadata {

String name;
Map<String, Metadata> originalMetadata;
List<Metadata> originalMetadata;
}
4 changes: 2 additions & 2 deletions src/main/java/dev/openfeature/sdk/multiprovider/Strategy.java
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Expand Up @@ -3,7 +3,7 @@
import dev.openfeature.sdk.EvaluationContext;
import dev.openfeature.sdk.FeatureProvider;
import dev.openfeature.sdk.ProviderEvaluation;
import java.util.Map;
import java.util.List;
import java.util.function.Function;

/**
Expand Down Expand Up @@ -34,7 +34,7 @@ public interface Strategy {
* @return the resolved {@link ProviderEvaluation}
*/
<T> ProviderEvaluation<T> evaluate(
Map<String, FeatureProvider> providers,
List<FeatureProvider> providers,

@coderabbitai coderabbitai Bot Jul 30, 2026

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📐 Maintainability & Code Quality | 🟡 Minor | ⚡ Quick win

Update the provider parameter documentation.

The @param providers text at Line 28 still says “ordered map,” although this method now receives a List<FeatureProvider>. Document that list order is significant and duplicate provider names are preserved.

🤖 Prompt for AI Agents 
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@src/main/java/dev/openfeature/sdk/multiprovider/Strategy.java` at line 37,
Update the `@param` providers documentation for the affected method in Strategy to
describe the List<FeatureProvider> accurately: state that provider order is
significant and duplicate provider names are preserved, removing the outdated
“ordered map” wording.

String key,
T defaultValue,
EvaluationContext ctx,
Expand Down
13 changes: 7 additions & 6 deletions src/test/java/dev/openfeature/sdk/multiprovider/BaseStrategyTest.java
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Expand Up @@ -13,8 +13,9 @@
import dev.openfeature.sdk.Value;
import dev.openfeature.sdk.providers.memory.Flag;
import dev.openfeature.sdk.providers.memory.InMemoryProvider;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import org.junit.jupiter.api.BeforeEach;

Expand All @@ -31,7 +32,7 @@ public abstract class BaseStrategyTest {
protected InMemoryProvider inMemoryProvider1;
protected InMemoryProvider inMemoryProvider2;

protected Map<String, FeatureProvider> orderedProviders;
protected List<FeatureProvider> orderedProviders;

protected EvaluationContext contextWithNewProvider;

Expand Down Expand Up @@ -84,10 +85,10 @@ public Metadata getMetadata() {
}

protected void setupOrderedProviders() {
orderedProviders = new LinkedHashMap<>();
orderedProviders.put("provider1", mockProvider1);
orderedProviders.put("provider2", mockProvider2);
orderedProviders.put("provider3", mockProvider3);
orderedProviders = new ArrayList<>(3);
orderedProviders.add(mockProvider1);
orderedProviders.add(mockProvider2);
orderedProviders.add(mockProvider3);
}

protected void setupEvaluationContexts() {
Expand Down
4 changes: 2 additions & 2 deletions src/test/java/dev/openfeature/sdk/multiprovider/FirstSuccessfulStrategyTest.java
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Expand Up @@ -134,8 +134,8 @@ void shouldCaptureExceptionDetailsFromThrowingProviders() {
@Test
void shouldReturnMultiProviderEvaluationForNonExistentFlag() {
orderedProviders.clear();
orderedProviders.put("old-provider", inMemoryProvider1);
orderedProviders.put("new-provider", inMemoryProvider2);
orderedProviders.add(inMemoryProvider1);
orderedProviders.add(inMemoryProvider2);
ProviderEvaluation<String> result = strategy.evaluate(
orderedProviders,
FLAG_KEY,
Expand Down
18 changes: 11 additions & 7 deletions src/test/java/dev/openfeature/sdk/multiprovider/MultiProviderTest.java
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Expand Up @@ -4,6 +4,7 @@
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertNotNull;
import static org.junit.jupiter.api.Assertions.assertThrows;
import static org.junit.jupiter.api.Assertions.assertTrue;
import static org.mockito.ArgumentMatchers.any;
import static org.mockito.ArgumentMatchers.eq;
import static org.mockito.ArgumentMatchers.isNull;
Expand Down Expand Up @@ -53,9 +54,9 @@ void shouldInitializeSuccessfully() {
multiProvider.initialize(null);

MultiProviderMetadata metadata = (MultiProviderMetadata) multiProvider.getMetadata();
Map<String, Metadata> map = metadata.getOriginalMetadata();
assertEquals(mockMetaData1, map.get(mockProvider1.getMetadata().getName()));
assertEquals(mockMetaData2, map.get(mockProvider2.getMetadata().getName()));
List<Metadata> list = metadata.getOriginalMetadata();
assertTrue(list.contains(mockMetaData1));
assertTrue(list.contains(mockMetaData2));
assertEquals("multiprovider", multiProvider.getMetadata().getName());
}

Expand Down Expand Up @@ -165,8 +166,8 @@ void shouldRetrieveCorrectMetadataName() {
MultiProvider multiProvider = new MultiProvider(providers, mockStrategy);
multiProvider.initialize(null);
MultiProviderMetadata metadata = (MultiProviderMetadata) multiProvider.getMetadata();
Map<String, Metadata> map = metadata.getOriginalMetadata();
assertEquals(mockMetaData1, map.get(mockProvider1.getMetadata().getName()));
List<Metadata> list = metadata.getOriginalMetadata();
assertTrue(list.contains(mockMetaData1));
}

@SneakyThrows
Expand Down Expand Up @@ -202,7 +203,7 @@ void shouldWorkWithCustomStrategy() {

@Override
public <T> ProviderEvaluation<T> evaluate(
Map<String, FeatureProvider> providers,
List<FeatureProvider> providers,
String key,
T defaultValue,
EvaluationContext ctx,
Expand All @@ -214,7 +215,10 @@ public <T> ProviderEvaluation<T> evaluate(
}

if (contextProvider != null && "new-provider".equals(contextProvider.asString())) {
return providerFunction.apply(providers.get("new-provider"));
return providerFunction.apply(providers.stream()
.filter(p -> "new-provider".equals(p.getMetadata().getName()))
Comment thread
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.findFirst()
.orElseThrow());
}
return fallbackStrategy.evaluate(providers, key, defaultValue, ctx, providerFunction);
}
Expand Down
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