Package org.eclipse.aether.util.graph.transformer

Class ClassicConflictResolver

java.lang.Object

org.eclipse.aether.util.graph.transformer.ConflictResolver

org.eclipse.aether.util.graph.transformer.ClassicConflictResolver

All Implemented Interfaces:

org.eclipse.aether.collection.DependencyGraphTransformer

public final class ClassicConflictResolver
extends ConflictResolver

A legacy dependency graph transformer that resolves version and scope conflicts among dependencies. This implementation maintains backward compatibility with Maven 3.x and Resolver 1.x behavior but has O(N²) worst-case performance characteristics. For new projects, consider using PathConflictResolver.

For a given set of conflicting nodes, one node will be chosen as the winner. How losing nodes are handled depends on the configured verbosity level: they may be removed entirely, have their children removed, or be left in place with conflict information. The exact rules by which a winning node and its effective scope are determined are controlled by user-supplied implementations of ConflictResolver.VersionSelector, ConflictResolver.ScopeSelector, ConflictResolver.OptionalitySelector and ConflictResolver.ScopeDeriver.

Performance Characteristics:

• Time Complexity: O(N²) worst-case where N is the number of dependency nodes
• Memory Usage: Modifies the dependency graph in-place
• Scalability: Performance degrades significantly on large multi-module projects

Algorithm Overview:

1. Depth-First Traversal: Walks the dependency graph depth-first
2. In-Place Modification: Modifies nodes directly during traversal
3. Conflict Detection: Identifies conflicts by comparing conflict IDs
4. Winner Selection: Uses provided selectors to choose winners
5. Loser Removal: Removes or marks losing nodes during traversal

When to Use:

• Exact backward compatibility with Maven 3.x/Resolver 1.x is required
• Debugging performance differences between old and new algorithms
• Small projects where performance is not a concern
• Testing and validation scenarios

Migration Recommendation: New projects should use PathConflictResolver for better performance. This implementation is retained primarily for compatibility and testing purposes.

Implementation Note: This conflict resolver is identical to the one used in Maven 3/Resolver 1.x. The implementation may produce O(N²) worst-case performance on projects with many small conflict groups (typically one member each), which is common in large multi-module projects.

Since:

2.0.11

See Also:

PathConflictResolver

Nested Class Summary

Nested classes/interfaces inherited from class org.eclipse.aether.util.graph.transformer.ConflictResolver

ConflictResolver.OptionalitySelector, ConflictResolver.ScopeDeriver, ConflictResolver.ScopeSelector, ConflictResolver.Verbosity, ConflictResolver.VersionSelector

Field Summary

Fields inherited from class org.eclipse.aether.util.graph.transformer.ConflictResolver

AUTO_CONFLICT_RESOLVER, CLASSIC_CONFLICT_RESOLVER, CONFIG_PROP_CONFLICT_RESOLVER_IMPL, CONFIG_PROP_VERBOSE, DEFAULT_CONFLICT_RESOLVER_IMPL, NODE_DATA_ORIGINAL_OPTIONALITY, NODE_DATA_ORIGINAL_SCOPE, NODE_DATA_WINNER, PATH_CONFLICT_RESOLVER

Constructor Summary

Constructors

Constructor	Description
ClassicConflictResolver(ConflictResolver.VersionSelector versionSelector, ConflictResolver.ScopeSelector scopeSelector, ConflictResolver.OptionalitySelector optionalitySelector, ConflictResolver.ScopeDeriver scopeDeriver)	Creates a new conflict resolver instance with the specified hooks.

Method Summary

Modifier and Type	Method	Description
org.eclipse.aether.graph.DependencyNode	transformGraph(org.eclipse.aether.graph.DependencyNode node, org.eclipse.aether.collection.DependencyGraphTransformationContext context)

Methods inherited from class org.eclipse.aether.util.graph.transformer.ConflictResolver

getVerbosity

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ClassicConflictResolver

public ClassicConflictResolver(ConflictResolver.VersionSelector versionSelector,
                               ConflictResolver.ScopeSelector scopeSelector,
                               ConflictResolver.OptionalitySelector optionalitySelector,
                               ConflictResolver.ScopeDeriver scopeDeriver)

Creates a new conflict resolver instance with the specified hooks.

Parameters:

versionSelector - the version selector to use, must not be null

scopeSelector - the scope selector to use, must not be null

optionalitySelector - the optionality selector ot use, must not be null

scopeDeriver - the scope deriver to use, must not be null

Method Detail

transformGraph

public org.eclipse.aether.graph.DependencyNode transformGraph(org.eclipse.aether.graph.DependencyNode node,
                                                              org.eclipse.aether.collection.DependencyGraphTransformationContext context)
                                                       throws org.eclipse.aether.RepositoryException

Specified by:

transformGraph in interface org.eclipse.aether.collection.DependencyGraphTransformer

Overrides:

transformGraph in class ConflictResolver

Throws:

org.eclipse.aether.RepositoryException