gnodet opened a new pull request, #11401:
URL: https://github.com/apache/maven/pull/11401
## 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
```java
// 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](https://www.augmentcode.com/) with
guidance from the PR author
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