Add @Aggregate annotation for Maven DI collection contributions

[gnodet]

Overview

This PR introduces the @Aggregate annotation to Maven's dependency injection framework, enabling modular contribution to aggregated collections without replacing the entire collection.

Key Features

• @aggregate annotation for @Provides methods that return List<T> or Map<String, T>
• Multiple contributors: Allows multiple modules to contribute entries to the same collection
• Preserves auto-aggregation: Maintains existing auto-aggregation behavior while enabling explicit contributions
• Priority support: Supports priority-based ordering for List<T> aggregations

Behavior

1. Without @aggregate: An explicit @Provides method for List<T> or Map<String, T> replaces the auto-aggregated collection entirely
2. With @aggregate: The @Provides method contributes entries to the auto-aggregated collection, allowing multiple providers to coexist
3. Mixed mode: If both @Aggregate and non-@Aggregate providers exist, the non-@Aggregate provider takes precedence

Use Cases

• Plugin architecture: Different modules can register services without depending on a central registry
• Lifecycle providers: Multiple modules can contribute lifecycle phases
• Extensible service registries: Core and extension modules can contribute services to the same map/list

Implementation Details

• New Binding.BindingToMethod class to track the source method for bindings
• Enhanced InjectorImpl with aggregation logic for List and Map injection
• Support for @Priority ordering in aggregated lists
• Comprehensive test coverage with 30+ test cases

Example Usage

// Module A
@Provides
@Aggregate
Map<String, LifecycleProvider> lifecycleProviders() {
    return Map.of("clean", new CleanLifecycle());
}

// Module B
@Provides
@Aggregate
Map<String, LifecycleProvider> moreLifecycleProviders() {
    return Map.of("deploy", new DeployLifecycle());
}

// Consumer
@Inject
Map<String, LifecycleProvider> allLifecycles; // Contains all contributions

Files Changed

• api/maven-api-di/src/main/java/org/apache/maven/api/di/Aggregate.java - New annotation with comprehensive documentation
• impl/maven-di/src/main/java/org/apache/maven/di/impl/Binding.java - Added BindingToMethod class
• impl/maven-di/src/main/java/org/apache/maven/di/impl/InjectorImpl.java - Aggregation logic implementation
• impl/maven-di/src/main/java/org/apache/maven/di/impl/ReflectionUtils.java - Updated to use BindingToMethod
• impl/maven-di/src/test/java/org/apache/maven/di/impl/InjectorImplTest.java - Comprehensive test coverage

Testing

Added 30+ test cases covering:

• Basic map and list aggregation
• Multiple @Aggregate providers
• Explicit providers (with and without @Aggregate)
• Priority ordering
• Empty collections
• Duplicate keys
• Mixed scenarios
• Integration with existing DI features

---

Pull Request opened by Augment Code with guidance from the PR author