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https://issues.apache.org/jira/browse/MNG-6732?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Guillaume Nodet updated MNG-6732:
---------------------------------
Fix Version/s: 4.x / Backlog
> DefaultArtifactDescriptorReader.loadPom to check IGNORE_MISSING policy upon
> ArtifactTransferException
> -----------------------------------------------------------------------------------------------------
>
> Key: MNG-6732
> URL: https://issues.apache.org/jira/browse/MNG-6732
> Project: Maven
> Issue Type: Improvement
> Components: Core
> Affects Versions: 3.6.1
> Reporter: Tomo Suzuki
> Priority: Major
> Fix For: 4.0.x-candidate, 4.x / Backlog
>
> Attachments: 62884438-89260580-bd04-11e9-8c4a-897d4b736dc7.png
>
> Time Spent: 0.5h
> Remaining Estimate: 0h
>
> h1. Problem
> Sometimes [Linkage Checker enforcer
> rule|https://github.com/GoogleCloudPlatform/cloud-opensource-java/tree/master/enforcer-rules]
> does not receive resolved artifact list because of a missing artifact even
> when the missing artifact is unused after Maven's dependency mediation.
> h1. Background
> The enforcer rule fails to retrieve artifact list through
> {{DefaultProjectDependenciesResolver.resolve}} when applied to
> [grpc-java-by-example/chat-example/chat-vaadin-client|https://github.com/saturnism/grpc-java-by-example/tree/master/chat-example/chat-vaadin-client]
> because of the missing {{xerces:xerces-impl:2.6.2}}, even though the
> artifact does not appear in the final dependency graph. The artifact does not
> appear in the graph because of Maven's dependency mediation.
> Artifact xerces:xerces-impl:2.6.2 is not published in Maven Central.
> In contrast, the enforcer rule can retrieve artifact list when applied to
> [https://github.com/suztomo/spring-cloud-gcp/tree/v1.1.2-linkage-checker]
> project even though it outputs "[WARNING] The POM for
> xerces:xerces-impl:jar:2.6.2 is missing, no dependency information
> available". The missing artifact does not appear in final dependency graph.
> [https://github.com/GoogleCloudPlatform/cloud-opensource-java/issues/834]
> h1. Diagnosis
> Currently {{DefaultArtifactDescriptorReader.loadPom}} method checks
> "ArtifactDescriptorPolicy.IGNORE_MISSING" policy upon
> ArtifactNotFoundException. This allows
> {{DefaultProjectDependenciesResolver.resolve}} calls
> {{repoSystem.resolveDependencies}} to obtain partially resolved artifact
> list, rather than failing entirely, when there is a missing artifact (such as
> {{xerces:xerces-impl:2.6.2}})
> However, when a retired Maven repository is involved (such as
> [http://repository.codehaus.org/] ),
> {{DefaultArtifactDescriptorReader.loadPom}} gets an ArtifactTransferException
> and throws ArtifactDescriptorException without checking
> "ArtifactDescriptorPolicy.IGNORE_MISSING" policy (excerpt below), and thus
> {{DefaultProjectDependenciesResolver.resolve}} does not return partially
> resolved artifact list.
> {code:java}
> catch ( ArtifactResolutionException e )
> {
> if ( e.getCause() instanceof ArtifactNotFoundException )
> {
> missingDescriptor( session, trace, a, (Exception)
> e.getCause() );
> if ( ( getPolicy( session, a, request ) &
> ArtifactDescriptorPolicy.IGNORE_MISSING ) != 0 )
> {
> return null;
> }
> }
> result.addException( e );
> throw new ArtifactDescriptorException( result );
> }
> {code}
> from
> [DefaultArtifactDescriptorReader.java|https://github.com/apache/maven/blob/d3ace78/maven-resolver-provider/src/main/java/org/apache/maven/repository/internal/DefaultArtifactDescriptorReader.java#L255]
> ArtifactNotFoundException is a special case of
> [ArtifactTransferException|https://maven.apache.org/resolver/apidocs/org/eclipse/aether/transfer/ArtifactTransferException.html].
> h1. Example Project
> Example project to demonstrate the diagnosis:
> [https://github.com/suztomo/maven-missing-artifact] . In this example, even
> though module-b and module-c have the same dependency section, module-c fails
> to run Maven because of a repository section containing a retired repository
> URL.
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