# SkillPatch skill: azure-appconfiguration-java

This skill provides guidance for using the Azure App Configuration SDK for Java, covering client creation, authentication methods (connection string and Entra ID), and configuration setting operations. It includes installation instructions, environment variable setup, and code examples for both sync and async clients. The skill helps agents integrate centralized application configuration management with key-value settings, feature flags, and snapshots into Java applications.

You (the agent) were given this URL and asked to use this skill. This is a **public** skill — no SkillPatch account, API key, or prior setup is required. Two ways to use it:

**1. Use it right now** — the skill's complete file tree (SKILL.md + all reference files) is inlined below; read `SKILL.md` first, then follow it, consulting the other files as it directs.

**2. Install the exact package onto disk** (recommended if you can run a shell — this reproduces the skill byte-for-byte, including any binary assets that can't be inlined):

```bash
mkdir -p .claude/skills/azure-appconfiguration-java
curl -sSL https://skillpatch.dev/install_skill/azure-appconfiguration-java | tar -xz -C .claude/skills/
```

(`.claude/skills/` is Claude Code's convention; use whatever directory your agent loads skills from.)


---

## Skill files (2)

- `SKILL.md`
- `references/examples.md`


### `SKILL.md`

````markdown
---
name: azure-appconfiguration-java
description: |
  Azure App Configuration SDK for Java. Centralized application configuration management with key-value settings, feature flags, and snapshots.
  Triggers: "ConfigurationClient java", "app configuration java", "feature flag java", "configuration setting java", "azure config java".
license: MIT
metadata:
  author: Microsoft
  version: "1.0.0"
  package: com.azure:azure-data-appconfiguration
---

# Azure App Configuration SDK for Java

Client library for Azure App Configuration, a managed service for centralizing application configurations.

## Installation

```xml
<dependency>
    <groupId>com.azure</groupId>
    <artifactId>azure-data-appconfiguration</artifactId>
    <version>1.8.0</version>
</dependency>
```

Or use Azure SDK BOM:

```xml
<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>com.azure</groupId>
            <artifactId>azure-sdk-bom</artifactId>
            <version>{bom_version}</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

<dependencies>
    <dependency>
        <groupId>com.azure</groupId>
        <artifactId>azure-data-appconfiguration</artifactId>
    </dependency>
</dependencies>
```

## Prerequisites

- Azure App Configuration store
- Connection string or Entra ID credentials

## Environment Variables

```bash
AZURE_APPCONFIG_CONNECTION_STRING=Endpoint=https://<store>.azconfig.io;Id=<id>;Secret=<secret>  # Alternative to Entra ID auth
AZURE_APPCONFIG_ENDPOINT=https://<store>.azconfig.io  # Required for all auth methods
AZURE_TOKEN_CREDENTIALS=prod  # Required only if DefaultAzureCredential is used in production
```

## Client Creation

### With Connection String

```java
import com.azure.data.appconfiguration.ConfigurationClient;
import com.azure.data.appconfiguration.ConfigurationClientBuilder;

ConfigurationClient configClient = new ConfigurationClientBuilder()
    .connectionString(System.getenv("AZURE_APPCONFIG_CONNECTION_STRING"))
    .buildClient();
```

### Async Client

```java
import com.azure.data.appconfiguration.ConfigurationAsyncClient;

ConfigurationAsyncClient asyncClient = new ConfigurationClientBuilder()
    .connectionString(connectionString)
    .buildAsyncClient();
```

### With Entra ID (Recommended)

```java
import com.azure.core.credential.TokenCredential;
import com.azure.identity.AzureIdentityEnvVars;
import com.azure.identity.DefaultAzureCredentialBuilder;
import com.azure.identity.ManagedIdentityCredentialBuilder;

// Local dev: DefaultAzureCredential. Production: set AZURE_TOKEN_CREDENTIALS=prod or AZURE_TOKEN_CREDENTIALS=<specific_credential>
TokenCredential credential = new DefaultAzureCredentialBuilder()
    .requireEnvVars(AzureIdentityEnvVars.AZURE_TOKEN_CREDENTIALS)
    .build();
// Or use a specific credential directly in production:
// See https://learn.microsoft.com/java/api/overview/azure/identity-readme?view=azure-java-stable#credential-classes
// TokenCredential credential = new ManagedIdentityCredentialBuilder().build();

ConfigurationClient configClient = new ConfigurationClientBuilder()
    .credential(credential)
    .endpoint(System.getenv("AZURE_APPCONFIG_ENDPOINT"))
    .buildClient();
```

## Key Concepts

| Concept | Description |
|---------|-------------|
| Configuration Setting | Key-value pair with optional label |
| Label | Dimension for separating settings (e.g., environments) |
| Feature Flag | Special setting for feature management |
| Secret Reference | Setting pointing to Key Vault secret |
| Snapshot | Point-in-time immutable view of settings |

## Configuration Setting Operations

### Create Setting (Add)

Creates only if setting doesn't exist:

```java
import com.azure.data.appconfiguration.models.ConfigurationSetting;

ConfigurationSetting setting = configClient.addConfigurationSetting(
    "app/database/connection", 
    "Production", 
    "Server=prod.db.com;Database=myapp"
);
```

### Create or Update Setting (Set)

Creates or overwrites:

```java
ConfigurationSetting setting = configClient.setConfigurationSetting(
    "app/cache/enabled", 
    "Production", 
    "true"
);
```

### Get Setting

```java
ConfigurationSetting setting = configClient.getConfigurationSetting(
    "app/database/connection", 
    "Production"
);
System.out.println("Value: " + setting.getValue());
System.out.println("Content-Type: " + setting.getContentType());
System.out.println("Last Modified: " + setting.getLastModified());
```

### Conditional Get (If Changed)

```java
import com.azure.core.http.rest.Response;
import com.azure.core.util.Context;

Response<ConfigurationSetting> response = configClient.getConfigurationSettingWithResponse(
    setting,      // Setting with ETag
    null,         // Accept datetime
    true,         // ifChanged - only fetch if modified
    Context.NONE
);

if (response.getStatusCode() == 304) {
    System.out.println("Setting not modified");
} else {
    ConfigurationSetting updated = response.getValue();
}
```

### Update Setting

```java
ConfigurationSetting updated = configClient.setConfigurationSetting(
    "app/cache/enabled", 
    "Production", 
    "false"
);
```

### Conditional Update (If Unchanged)

```java
// Only update if ETag matches (no concurrent modifications)
Response<ConfigurationSetting> response = configClient.setConfigurationSettingWithResponse(
    setting,     // Setting with current ETag
    true,        // ifUnchanged
    Context.NONE
);
```

### Delete Setting

```java
ConfigurationSetting deleted = configClient.deleteConfigurationSetting(
    "app/cache/enabled", 
    "Production"
);
```

### Conditional Delete

```java
Response<ConfigurationSetting> response = configClient.deleteConfigurationSettingWithResponse(
    setting,     // Setting with ETag
    true,        // ifUnchanged
    Context.NONE
);
```

## List and Filter Settings

### List by Key Pattern

```java
import com.azure.data.appconfiguration.models.SettingSelector;
import com.azure.core.http.rest.PagedIterable;

SettingSelector selector = new SettingSelector()
    .setKeyFilter("app/*");

PagedIterable<ConfigurationSetting> settings = configClient.listConfigurationSettings(selector);
for (ConfigurationSetting s : settings) {
    System.out.println(s.getKey() + " = " + s.getValue());
}
```

### List by Label

```java
SettingSelector selector = new SettingSelector()
    .setKeyFilter("*")
    .setLabelFilter("Production");

PagedIterable<ConfigurationSetting> settings = configClient.listConfigurationSettings(selector);
```

### List by Multiple Keys

```java
SettingSelector selector = new SettingSelector()
    .setKeyFilter("app/database/*,app/cache/*");

PagedIterable<ConfigurationSetting> settings = configClient.listConfigurationSettings(selector);
```

### List Revisions

```java
SettingSelector selector = new SettingSelector()
    .setKeyFilter("app/database/connection");

PagedIterable<ConfigurationSetting> revisions = configClient.listRevisions(selector);
for (ConfigurationSetting revision : revisions) {
    System.out.println("Value: " + revision.getValue() + ", Modified: " + revision.getLastModified());
}
```

## Feature Flags

### Create Feature Flag

```java
import com.azure.data.appconfiguration.models.FeatureFlagConfigurationSetting;
import com.azure.data.appconfiguration.models.FeatureFlagFilter;
import java.util.Arrays;

FeatureFlagFilter percentageFilter = new FeatureFlagFilter("Microsoft.Percentage")
    .addParameter("Value", 50);

FeatureFlagConfigurationSetting featureFlag = new FeatureFlagConfigurationSetting("beta-feature", true)
    .setDescription("Beta feature rollout")
    .setClientFilters(Arrays.asList(percentageFilter));

FeatureFlagConfigurationSetting created = (FeatureFlagConfigurationSetting)
    configClient.addConfigurationSetting(featureFlag);
```

### Get Feature Flag

```java
FeatureFlagConfigurationSetting flag = (FeatureFlagConfigurationSetting)
    configClient.getConfigurationSetting(featureFlag);

System.out.println("Feature: " + flag.getFeatureId());
System.out.println("Enabled: " + flag.isEnabled());
System.out.println("Filters: " + flag.getClientFilters());
```

### Update Feature Flag

```java
featureFlag.setEnabled(false);
FeatureFlagConfigurationSetting updated = (FeatureFlagConfigurationSetting)
    configClient.setConfigurationSetting(featureFlag);
```

## Secret References

### Create Secret Reference

```java
import com.azure.data.appconfiguration.models.SecretReferenceConfigurationSetting;

SecretReferenceConfigurationSetting secretRef = new SecretReferenceConfigurationSetting(
    "app/secrets/api-key",
    "https://myvault.vault.azure.net/secrets/api-key"
);

SecretReferenceConfigurationSetting created = (SecretReferenceConfigurationSetting)
    configClient.addConfigurationSetting(secretRef);
```

### Get Secret Reference

```java
SecretReferenceConfigurationSetting ref = (SecretReferenceConfigurationSetting)
    configClient.getConfigurationSetting(secretRef);

System.out.println("Secret URI: " + ref.getSecretId());
```

## Read-Only Settings

### Set Read-Only

```java
ConfigurationSetting readOnly = configClient.setReadOnly(
    "app/critical/setting", 
    "Production", 
    true
);
```

### Clear Read-Only

```java
ConfigurationSetting writable = configClient.setReadOnly(
    "app/critical/setting", 
    "Production", 
    false
);
```

## Snapshots

### Create Snapshot

```java
import com.azure.data.appconfiguration.models.ConfigurationSnapshot;
import com.azure.data.appconfiguration.models.ConfigurationSettingsFilter;
import com.azure.core.util.polling.SyncPoller;
import com.azure.core.util.polling.PollOperationDetails;

List<ConfigurationSettingsFilter> filters = new ArrayList<>();
filters.add(new ConfigurationSettingsFilter("app/*"));

SyncPoller<PollOperationDetails, ConfigurationSnapshot> poller = configClient.beginCreateSnapshot(
    "release-v1.0",
    new ConfigurationSnapshot(filters),
    Context.NONE
);
poller.setPollInterval(Duration.ofSeconds(10));
poller.waitForCompletion();

ConfigurationSnapshot snapshot = poller.getFinalResult();
System.out.println("Snapshot: " + snapshot.getName() + ", Status: " + snapshot.getStatus());
```

### Get Snapshot

```java
ConfigurationSnapshot snapshot = configClient.getSnapshot("release-v1.0");
System.out.println("Created: " + snapshot.getCreatedAt());
System.out.println("Items: " + snapshot.getItemCount());
```

### List Settings in Snapshot

```java
PagedIterable<ConfigurationSetting> settings = 
    configClient.listConfigurationSettingsForSnapshot("release-v1.0");

for (ConfigurationSetting setting : settings) {
    System.out.println(setting.getKey() + " = " + setting.getValue());
}
```

### Archive Snapshot

```java
ConfigurationSnapshot archived = configClient.archiveSnapshot("release-v1.0");
System.out.println("Status: " + archived.getStatus()); // archived
```

### Recover Snapshot

```java
ConfigurationSnapshot recovered = configClient.recoverSnapshot("release-v1.0");
System.out.println("Status: " + recovered.getStatus()); // ready
```

### List All Snapshots

```java
import com.azure.data.appconfiguration.models.SnapshotSelector;

SnapshotSelector selector = new SnapshotSelector().setNameFilter("release-*");
PagedIterable<ConfigurationSnapshot> snapshots = configClient.listSnapshots(selector);

for (ConfigurationSnapshot snap : snapshots) {
    System.out.println(snap.getName() + " - " + snap.getStatus());
}
```

## Labels

### List Labels

```java
import com.azure.data.appconfiguration.models.SettingLabelSelector;

configClient.listLabels(new SettingLabelSelector().setNameFilter("*"))
    .forEach(label -> System.out.println("Label: " + label.getName()));
```

## Async Operations

```java
ConfigurationAsyncClient asyncClient = new ConfigurationClientBuilder()
    .connectionString(connectionString)
    .buildAsyncClient();

// Async list with reactive streams
asyncClient.listConfigurationSettings(new SettingSelector().setLabelFilter("Production"))
    .subscribe(
        setting -> System.out.println(setting.getKey() + " = " + setting.getValue()),
        error -> System.err.println("Error: " + error.getMessage()),
        () -> System.out.println("Completed")
    );
```

## Error Handling

```java
import com.azure.core.exception.HttpResponseException;

try {
    configClient.getConfigurationSetting("nonexistent", null);
} catch (HttpResponseException e) {
    if (e.getResponse().getStatusCode() == 404) {
        System.err.println("Setting not found");
    } else {
        System.err.println("Error: " + e.getMessage());
    }
}
```

## Best Practices

1. **Use labels** — Separate configurations by environment (Dev, Staging, Production)
2. **Use snapshots** — Create immutable snapshots for releases
3. **Feature flags** — Use for gradual rollouts and A/B testing
4. **Secret references** — Store sensitive values in Key Vault
5. **Conditional requests** — Use ETags for optimistic concurrency
6. **Read-only protection** — Lock critical production settings
7. **Use Entra ID** — Preferred over connection strings
8. **Async client** — Use for high-throughput scenarios

## Reference Links

| Resource | URL |
|----------|-----|
| Maven Package | https://central.sonatype.com/artifact/com.azure/azure-data-appconfiguration |
| GitHub | https://github.com/Azure/azure-sdk-for-java/tree/main/sdk/appconfiguration/azure-data-appconfiguration |
| API Documentation | https://aka.ms/java-docs |
| Product Docs | https://learn.microsoft.com/azure/azure-app-configuration |
| Samples | https://github.com/Azure/azure-sdk-for-java/tree/main/sdk/appconfiguration/azure-data-appconfiguration/src/samples |
| Troubleshooting | https://github.com/Azure/azure-sdk-for-java/blob/main/sdk/appconfiguration/azure-data-appconfiguration/TROUBLESHOOTING.md |

````


### `references/examples.md`

````markdown
# Azure App Configuration Java SDK - Examples

Comprehensive code examples for the Azure App Configuration SDK for Java.

## Table of Contents

- [Maven Dependency](#maven-dependency)
- [Client Creation](#client-creation)
- [Configuration Settings CRUD](#configuration-settings-crud)
- [List and Filter Settings](#list-and-filter-settings)
- [Feature Flags](#feature-flags)
- [Secret References](#secret-references)
- [Read-Only Settings](#read-only-settings)
- [Snapshots](#snapshots)
- [Labels](#labels)
- [Async Operations](#async-operations)
- [Error Handling](#error-handling)
- [Complete Application Example](#complete-application-example)

## Maven Dependency

```xml
<dependency>
    <groupId>com.azure</groupId>
    <artifactId>azure-data-appconfiguration</artifactId>
    <version>1.8.0</version>
</dependency>

<!-- For DefaultAzureCredential -->
<dependency>
    <groupId>com.azure</groupId>
    <artifactId>azure-identity</artifactId>
    <version>1.14.2</version>
</dependency>
```

Or use Azure SDK BOM:

```xml
<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>com.azure</groupId>
            <artifactId>azure-sdk-bom</artifactId>
            <version>1.2.28</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

<dependencies>
    <dependency>
        <groupId>com.azure</groupId>
        <artifactId>azure-data-appconfiguration</artifactId>
    </dependency>
</dependencies>
```

## Client Creation

### With Connection String

```java
import com.azure.data.appconfiguration.ConfigurationClient;
import com.azure.data.appconfiguration.ConfigurationClientBuilder;

String connectionString = System.getenv("AZURE_APPCONFIG_CONNECTION_STRING");

ConfigurationClient client = new ConfigurationClientBuilder()
    .connectionString(connectionString)
    .buildClient();
```

### With Entra ID (Recommended)

```java
import com.azure.identity.DefaultAzureCredentialBuilder;

String endpoint = System.getenv("AZURE_APPCONFIG_ENDPOINT");

ConfigurationClient client = new ConfigurationClientBuilder()
    .credential(new DefaultAzureCredentialBuilder().build())
    .endpoint(endpoint)
    .buildClient();
```

### Async Client

```java
import com.azure.data.appconfiguration.ConfigurationAsyncClient;

ConfigurationAsyncClient asyncClient = new ConfigurationClientBuilder()
    .credential(new DefaultAzureCredentialBuilder().build())
    .endpoint(endpoint)
    .buildAsyncClient();
```

## Configuration Settings CRUD

### Create Setting (Add)

Creates only if setting doesn't exist:

```java
import com.azure.data.appconfiguration.models.ConfigurationSetting;

// Add with key, label, and value
ConfigurationSetting setting = client.addConfigurationSetting(
    "app/database/connection",    // key
    "Production",                  // label (can be null)
    "Server=prod.db.com;Database=myapp"  // value
);

System.out.println("Setting created:");
System.out.println("  Key: " + setting.getKey());
System.out.println("  Label: " + setting.getLabel());
System.out.println("  Value: " + setting.getValue());
System.out.println("  ETag: " + setting.getETag());
```

### Create or Update Setting (Set)

Creates or overwrites:

```java
ConfigurationSetting setting = client.setConfigurationSetting(
    "app/cache/enabled",
    "Production",
    "true"
);

System.out.println("Setting set: " + setting.getKey() + " = " + setting.getValue());
```

### Create with ConfigurationSetting Object

```java
ConfigurationSetting newSetting = new ConfigurationSetting()
    .setKey("app/feature/timeout")
    .setLabel("Production")
    .setValue("30000")
    .setContentType("application/json");

ConfigurationSetting created = client.addConfigurationSetting(newSetting);
```

### Get Setting

```java
ConfigurationSetting setting = client.getConfigurationSetting(
    "app/database/connection",
    "Production"
);

System.out.println("=== Setting Details ===");
System.out.println("Key: " + setting.getKey());
System.out.println("Label: " + setting.getLabel());
System.out.println("Value: " + setting.getValue());
System.out.println("Content-Type: " + setting.getContentType());
System.out.println("Last Modified: " + setting.getLastModified());
System.out.println("ETag: " + setting.getETag());
System.out.println("Read-Only: " + setting.isReadOnly());
```

### Conditional Get (If Changed)

Only fetch if modified since last retrieval:

```java
import com.azure.core.http.rest.Response;
import com.azure.core.util.Context;

// First, get the setting with its ETag
ConfigurationSetting setting = client.getConfigurationSetting("app/cache/enabled", "Production");

// Later, check if it changed
Response<ConfigurationSetting> response = client.getConfigurationSettingWithResponse(
    setting,      // Setting with ETag
    null,         // Accept datetime
    true,         // ifChanged - only fetch if modified
    Context.NONE
);

if (response.getStatusCode() == 304) {
    System.out.println("Setting not modified since last fetch");
} else {
    ConfigurationSetting updated = response.getValue();
    System.out.println("Setting was modified: " + updated.getValue());
}
```

### Update Setting

```java
// Simple update
ConfigurationSetting updated = client.setConfigurationSetting(
    "app/cache/enabled",
    "Production",
    "false"
);

System.out.println("Updated value: " + updated.getValue());
```

### Conditional Update (If Unchanged)

Only update if no concurrent modifications:

```java
// Get current setting with ETag
ConfigurationSetting current = client.getConfigurationSetting("app/timeout", "Production");

// Modify the value
current.setValue("60000");

// Update only if ETag matches (optimistic concurrency)
Response<ConfigurationSetting> response = client.setConfigurationSettingWithResponse(
    current,     // Setting with current ETag
    true,        // ifUnchanged - only update if ETag matches
    Context.NONE
);

if (response.getStatusCode() == 200) {
    System.out.println("Update successful");
} else {
    System.out.println("Conflict - setting was modified by another process");
}
```

### Delete Setting

```java
ConfigurationSetting deleted = client.deleteConfigurationSetting(
    "app/cache/enabled",
    "Production"
);

if (deleted != null) {
    System.out.println("Deleted setting: " + deleted.getKey());
}
```

### Conditional Delete

```java
Response<ConfigurationSetting> response = client.deleteConfigurationSettingWithResponse(
    setting,     // Setting with ETag
    true,        // ifUnchanged
    Context.NONE
);

if (response.getStatusCode() == 200) {
    System.out.println("Setting deleted");
}
```

## List and Filter Settings

### List All Settings

```java
import com.azure.data.appconfiguration.models.SettingSelector;
import com.azure.core.http.rest.PagedIterable;

PagedIterable<ConfigurationSetting> settings = client.listConfigurationSettings(
    new SettingSelector()
);

System.out.println("=== All Settings ===");
for (ConfigurationSetting s : settings) {
    System.out.printf("%s [%s] = %s%n", s.getKey(), s.getLabel(), s.getValue());
}
```

### List by Key Pattern

```java
SettingSelector selector = new SettingSelector()
    .setKeyFilter("app/*");  // Wildcard pattern

PagedIterable<ConfigurationSetting> settings = client.listConfigurationSettings(selector);

for (ConfigurationSetting s : settings) {
    System.out.println(s.getKey() + " = " + s.getValue());
}
```

### List by Label

```java
SettingSelector selector = new SettingSelector()
    .setKeyFilter("*")
    .setLabelFilter("Production");

PagedIterable<ConfigurationSetting> settings = client.listConfigurationSettings(selector);
```

### List by Multiple Keys

```java
SettingSelector selector = new SettingSelector()
    .setKeyFilter("app/database/*,app/cache/*");  // Comma-separated patterns

PagedIterable<ConfigurationSetting> settings = client.listConfigurationSettings(selector);
```

### List Null Labels Only

```java
SettingSelector selector = new SettingSelector()
    .setKeyFilter("*")
    .setLabelFilter("\0");  // Null label filter

PagedIterable<ConfigurationSetting> settings = client.listConfigurationSettings(selector);
```

### Select Specific Fields

```java
import com.azure.data.appconfiguration.models.SettingFields;
import java.util.EnumSet;

SettingSelector selector = new SettingSelector()
    .setKeyFilter("*")
    .setFields(EnumSet.of(SettingFields.KEY, SettingFields.VALUE, SettingFields.LAST_MODIFIED));

PagedIterable<ConfigurationSetting> settings = client.listConfigurationSettings(selector);
```

### List Revisions

View history of changes:

```java
SettingSelector selector = new SettingSelector()
    .setKeyFilter("app/database/connection");

PagedIterable<ConfigurationSetting> revisions = client.listRevisions(selector);

System.out.println("=== Setting Revisions ===");
for (ConfigurationSetting revision : revisions) {
    System.out.printf("Value: %s, Modified: %s%n",
        revision.getValue(),
        revision.getLastModified());
}
```

## Feature Flags

### Create Feature Flag

```java
import com.azure.data.appconfiguration.models.FeatureFlagConfigurationSetting;
import com.azure.data.appconfiguration.models.FeatureFlagFilter;
import java.util.Arrays;

// Simple feature flag
FeatureFlagConfigurationSetting simpleFlag = new FeatureFlagConfigurationSetting("dark-mode", true)
    .setDescription("Enable dark mode theme");

client.addConfigurationSetting(simpleFlag);

// Feature flag with percentage filter
FeatureFlagFilter percentageFilter = new FeatureFlagFilter("Microsoft.Percentage")
    .addParameter("Value", 50);  // 50% rollout

FeatureFlagConfigurationSetting betaFlag = new FeatureFlagConfigurationSetting("beta-feature", true)
    .setDescription("Beta feature with gradual rollout")
    .setClientFilters(Arrays.asList(percentageFilter));

FeatureFlagConfigurationSetting created = (FeatureFlagConfigurationSetting)
    client.addConfigurationSetting(betaFlag);

System.out.println("Feature flag created: " + created.getFeatureId());
```

### Create Feature Flag with Targeting Filter

```java
import java.util.HashMap;
import java.util.Map;

Map<String, Object> targetingParams = new HashMap<>();
targetingParams.put("Audience", Map.of(
    "Users", Arrays.asList("user1@example.com", "user2@example.com"),
    "Groups", Arrays.asList(
        Map.of("Name", "beta-testers", "RolloutPercentage", 100),
        Map.of("Name", "employees", "RolloutPercentage", 50)
    ),
    "DefaultRolloutPercentage", 10
));

FeatureFlagFilter targetingFilter = new FeatureFlagFilter("Microsoft.Targeting")
    .setParameters(targetingParams);

FeatureFlagConfigurationSetting targetedFlag = new FeatureFlagConfigurationSetting("new-dashboard", true)
    .setDescription("New dashboard with targeted rollout")
    .setClientFilters(Arrays.asList(targetingFilter));

client.addConfigurationSetting(targetedFlag);
```

### Get Feature Flag

```java
FeatureFlagConfigurationSetting flag = (FeatureFlagConfigurationSetting)
    client.getConfigurationSetting(
        ".appconfig.featureflag/beta-feature",  // Key format for feature flags
        null
    );

System.out.println("=== Feature Flag ===");
System.out.println("Feature ID: " + flag.getFeatureId());
System.out.println("Enabled: " + flag.isEnabled());
System.out.println("Description: " + flag.getDescription());
System.out.println("Filters: " + flag.getClientFilters());
```

### Update Feature Flag

```java
FeatureFlagConfigurationSetting flag = (FeatureFlagConfigurationSetting)
    client.getConfigurationSetting(".appconfig.featureflag/beta-feature", null);

// Disable the feature
flag.setEnabled(false);

FeatureFlagConfigurationSetting updated = (FeatureFlagConfigurationSetting)
    client.setConfigurationSetting(flag);

System.out.println("Feature flag updated. Enabled: " + updated.isEnabled());
```

### List Feature Flags

```java
SettingSelector selector = new SettingSelector()
    .setKeyFilter(".appconfig.featureflag/*");

PagedIterable<ConfigurationSetting> flags = client.listConfigurationSettings(selector);

System.out.println("=== Feature Flags ===");
for (ConfigurationSetting setting : flags) {
    if (setting instanceof FeatureFlagConfigurationSetting) {
        FeatureFlagConfigurationSetting flag = (FeatureFlagConfigurationSetting) setting;
        System.out.printf("%s: %s%n", flag.getFeatureId(), flag.isEnabled() ? "ON" : "OFF");
    }
}
```

## Secret References

### Create Secret Reference

```java
import com.azure.data.appconfiguration.models.SecretReferenceConfigurationSetting;

SecretReferenceConfigurationSetting secretRef = new SecretReferenceConfigurationSetting(
    "app/secrets/api-key",                                    // Key
    "https://myvault.vault.azure.net/secrets/api-key"        // Key Vault secret URI
);

SecretReferenceConfigurationSetting created = (SecretReferenceConfigurationSetting)
    client.addConfigurationSetting(secretRef);

System.out.println("Secret reference created: " + created.getKey());
System.out.println("Points to: " + created.getSecretId());
```

### Get Secret Reference

```java
SecretReferenceConfigurationSetting ref = (SecretReferenceConfigurationSetting)
    client.getConfigurationSetting("app/secrets/api-key", null);

System.out.println("Secret URI: " + ref.getSecretId());

// To get the actual secret value, use Key Vault SDK
// SecretClient kvClient = new SecretClientBuilder()...
// KeyVaultSecret secret = kvClient.getSecret("api-key");
```

### Update Secret Reference

```java
SecretReferenceConfigurationSetting ref = (SecretReferenceConfigurationSetting)
    client.getConfigurationSetting("app/secrets/api-key", null);

// Point to a different secret version
ref.setSecretId("https://myvault.vault.azure.net/secrets/api-key/abc123");

client.setConfigurationSetting(ref);
```

## Read-Only Settings

### Set Read-Only

```java
ConfigurationSetting readOnly = client.setReadOnly(
    "app/critical/setting",
    "Production",
    true  // isReadOnly
);

System.out.println("Setting is now read-only: " + readOnly.isReadOnly());
```

### Clear Read-Only

```java
ConfigurationSetting writable = client.setReadOnly(
    "app/critical/setting",
    "Production",
    false  // make writable
);

System.out.println("Setting is writable: " + !writable.isReadOnly());
```

## Snapshots

### Create Snapshot

```java
import com.azure.data.appconfiguration.models.ConfigurationSnapshot;
import com.azure.data.appconfiguration.models.ConfigurationSettingsFilter;
import com.azure.core.util.polling.SyncPoller;
import com.azure.core.util.polling.PollOperationDetails;
import java.time.Duration;
import java.util.ArrayList;
import java.util.List;

List<ConfigurationSettingsFilter> filters = new ArrayList<>();
filters.add(new ConfigurationSettingsFilter("app/*"));  // Include all app/* keys

SyncPoller<PollOperationDetails, ConfigurationSnapshot> poller = client.beginCreateSnapshot(
    "release-v1.0",
    new ConfigurationSnapshot(filters),
    Context.NONE
);

poller.setPollInterval(Duration.ofSeconds(10));
poller.waitForCompletion();

ConfigurationSnapshot snapshot = poller.getFinalResult();

System.out.println("=== Snapshot Created ===");
System.out.println("Name: " + snapshot.getName());
System.out.println("Status: " + snapshot.getStatus());
System.out.println("Item Count: " + snapshot.getItemCount());
System.out.println("Size: " + snapshot.getSizeInBytes() + " bytes");
System.out.println("Created: " + snapshot.getCreatedAt());
```

### Get Snapshot

```java
ConfigurationSnapshot snapshot = client.getSnapshot("release-v1.0");

System.out.println("Snapshot: " + snapshot.getName());
System.out.println("Status: " + snapshot.getStatus());
System.out.println("Items: " + snapshot.getItemCount());
System.out.println("Retention: " + snapshot.getRetentionPeriod());
```

### List Settings in Snapshot

```java
PagedIterable<ConfigurationSetting> settings = 
    client.listConfigurationSettingsForSnapshot("release-v1.0");

System.out.println("=== Settings in Snapshot ===");
for (ConfigurationSetting setting : settings) {
    System.out.printf("%s = %s%n", setting.getKey(), setting.getValue());
}
```

### Archive Snapshot

```java
ConfigurationSnapshot archived = client.archiveSnapshot("release-v1.0");
System.out.println("Status: " + archived.getStatus());  // archived
```

### Recover Snapshot

```java
ConfigurationSnapshot recovered = client.recoverSnapshot("release-v1.0");
System.out.println("Status: " + recovered.getStatus());  // ready
```

### List All Snapshots

```java
import com.azure.data.appconfiguration.models.SnapshotSelector;

SnapshotSelector selector = new SnapshotSelector()
    .setNameFilter("release-*");

PagedIterable<ConfigurationSnapshot> snapshots = client.listSnapshots(selector);

System.out.println("=== Snapshots ===");
for (ConfigurationSnapshot snap : snapshots) {
    System.out.printf("%s - %s (%d items)%n",
        snap.getName(),
        snap.getStatus(),
        snap.getItemCount());
}
```

## Labels

### List Labels

```java
import com.azure.data.appconfiguration.models.SettingLabelSelector;

PagedIterable<SettingLabel> labels = client.listLabels(
    new SettingLabelSelector().setNameFilter("*")
);

System.out.println("=== Labels ===");
for (SettingLabel label : labels) {
    System.out.println("Label: " + (label.getName() == null ? "(null)" : label.getName()));
}
```

## Async Operations

### Async List with Reactive Streams

```java
ConfigurationAsyncClient asyncClient = new ConfigurationClientBuilder()
    .credential(new DefaultAzureCredentialBuilder().build())
    .endpoint(endpoint)
    .buildAsyncClient();

asyncClient.listConfigurationSettings(new SettingSelector().setLabelFilter("Production"))
    .subscribe(
        setting -> System.out.println(setting.getKey() + " = " + setting.getValue()),
        error -> System.err.println("Error: " + error.getMessage()),
        () -> System.out.println("Completed listing")
    );

// Keep application running for async operations
Thread.sleep(5000);
```

### Async Get and Set

```java
asyncClient.getConfigurationSetting("app/timeout", "Production")
    .flatMap(setting -> {
        setting.setValue("45000");
        return asyncClient.setConfigurationSetting(setting);
    })
    .subscribe(
        updated -> System.out.println("Updated: " + updated.getValue()),
        error -> System.err.println("Error: " + error.getMessage())
    );
```

## Error Handling

```java
import com.azure.core.exception.HttpResponseException;
import com.azure.core.exception.ResourceNotFoundException;

try {
    ConfigurationSetting setting = client.getConfigurationSetting("nonexistent", null);
} catch (ResourceNotFoundException e) {
    System.err.println("Setting not found");
} catch (HttpResponseException e) {
    int statusCode = e.getResponse().getStatusCode();
    
    switch (statusCode) {
        case 401:
            System.err.println("Unauthorized - check credentials");
            break;
        case 403:
            System.err.println("Forbidden - check permissions");
            break;
        case 409:
            System.err.println("Conflict - setting already exists or ETag mismatch");
            break;
        case 412:
            System.err.println("Precondition failed - setting was modified");
            break;
        case 429:
            System.err.println("Rate limited - retry with backoff");
            break;
        default:
            System.err.println("Error: " + e.getMessage());
    }
}
```

## Complete Application Example

```java
import com.azure.data.appconfiguration.ConfigurationClient;
import com.azure.data.appconfiguration.ConfigurationClientBuilder;
import com.azure.data.appconfiguration.models.*;
import com.azure.core.http.rest.PagedIterable;
import com.azure.identity.DefaultAzureCredentialBuilder;

import java.util.*;

public class AppConfigurationManager {
    
    private final ConfigurationClient client;
    privat
...<truncated>
````