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https://issues.apache.org/jira/browse/MNG-7706?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17717271#comment-17717271
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ASF GitHub Bot commented on MNG-7706:
-------------------------------------

basil commented on PR #1012:
URL: https://github.com/apache/maven/pull/1012#issuecomment-1525911551

   > on `ProjectBuildingRequest` `setSession` from 2
   
   The `setSession` method does not exist, but a `setRepositorySession` exists. 
But why should I call that when `session.getProjectBuildingRequest()` already 
calls it a few lines above?




> Deprecate ${localRepository} mojo parameter expression
> ------------------------------------------------------
>
>                 Key: MNG-7706
>                 URL: https://issues.apache.org/jira/browse/MNG-7706
>             Project: Maven
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Tamas Cservenak
>            Assignee: Tamas Cservenak
>            Priority: Major
>             Fix For: 3.9.1, 4.0.0-alpha-5, 4.0.0
>
>
> The mojo parameter expression 'localRepository' injects type 
> {{ArtifactRepository}} that is part of the suite coming from Maven2 (predates 
> Mercury, that was superseded by Aether, today Maven Resolver).
> The problem with this interface is that it is not compatible (nor is possible 
> to adapt it) to Maven Resolver LocalRepositoryManager due lack of context. 
> Also, the use of this interface in Mojos causes issues like MNG-7663, as they 
> fully (and blindly) re-implement Maven local repository with *wired in* 
> layout.
> Moreover, Mojos using this expression are usually dragging other (legacy) 
> deprecated things as well, most typically maven-artifact-transfer, or 
> maven-dependency-tree and so on, all things that predates Maven 3.1 (are done 
> to "protect" from Aether package change happened between Maven 3.0 and Maven 
> 3.1). Today baseline for plugins is 3.2.5, so none of these "indirection" are 
> needed anymore. In fact, the use of this expression is very good sign of 
> legacy and technical debt present in given plugin. And also, these plugins 
> cripple Maven to adopt new features. This warning is a clear indicator for 
> legacy or neglected plugins.
> The type {{ArtifactRepository}} is used in Maven internally (most in 
> maven-compat, a bit less in maven-core), this is telling as well, but IMHO 
> there is no need to deprecate this interface, as:
>  * plugins who migrate from this ancient interface to Resolver will have much 
> simpler job with maven 4 API (as it is much closer to Resolver than old Maven 
> APIs)
>  * this tackles only Plugins, while Maven itself is fine, as post Maven 4 the 
> internals will be shut off, so warning Mojo authors is enough
>  * still, we should look into core where and why is this type used for
>  * deprecate localRepository used of {{ArtifactRepository}} type on 
> following: {{{}MavenExecutionRequest{}}}, {{MavenSession}} and 
> {{ProjectBuildingRequest}} as instance created for these are effectively not 
> used (and are created "too early" and they carry repository system session 
> anyway
> If a Mojo gets this WARNING, how should it be fixed?
>  * presence of parameter {{{}$\{localRepository{}}}} (with presence of type 
> ArtifactReposiory) usually means following things: Mojo uses maven-compat 
> Maven2 compatibility layer, OR uses some deprecated libraries (most prominent 
> example is maven-artifact-transfer). Both are technical debts, and remedy is 
> to switch code to use current APIs.
>  * second most often reason for parameter is access to the base directory of 
> local repository. In this case {{RepositorySystemSession}} should be injected 
> instead, use expression {{{}$\{repositorySystemSession{}}}} and get the 
> LocalRepositoryManager (LRM) from it. Word of warning: in most cases you DO 
> NOT want the base directory of local repository, as since Maven 3.9.0 the 
> layout of it is not fixed. If you want to access contents of local 
> repository, you *must use LRM APIs instead* (this is actually true since 
> Maven 3.0.x)!
> If user is stuck with plugin that issues this warning, user still can use it, 
> but should avoid use of any advanced (split, etc) local repository features, 
> available since 3.9.0. Inevitably, the deprecated APIs (maven-compat, etc) 
> will get removed in the future, so if no way to update the Mojo, user should 
> plan to migrate to some alternative solution (to buy out the affected Mojo).



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