This document outlines some of the steps that are being taken to ensure as much backward compatibility with tools and plugins
that are currently written against Maven 2.0.x.

h1. Affected Plugins

h2. Maven Remote Resources Plugin
* org.apache.maven.project.inheritance.ModelInheritanceAssembler#assembleModelInheritance: used to walk the POMs to find out all the license information. This 
  functionality has been superceded by the model properties-based system for POM construction. We provide the same functionality using the model
  properties-based system but have just placed the component as-is in the maven-compat package to ensure the default lifecycle functions.
* org.apache.maven.project.ProjectUtils: placed in the maven-compat package.
* org.apache.maven.project.MissingRepositoryElementException ... used by ProjectUtils

h2. Maven Help Plugin
* org.apache.maven.project.path.PathTranslator: used as a parameter in the EvaluateMojo. The path translator has been replaced the model builder
  and PomTransformer.
  
h1. Affected Components & Classes

h2. Maven Artifact

Maven Artifact will be entirely extricated from the core of Maven 3.x and replaced with Mercury, but we will make a best effort to 
ensure the compatibility of plugins that use Maven Artifact. There are, however, components and classes that are just so broken or conflict
with standard ways of doing resolution and conflict reduction that we can't support them.

h3. Supported Compatibility
* org.apache.maven.artifact.deployer.ArtifactDeployer
* org.apache.maven.artifact.factory.ArtifactFactory
* org.apache.maven.artifact.handler.ArtifactHandler
* org.apache.maven.artifact.installer.ArtifactInstaller
* org.apache.maven.artifact.manager.WagonManager
* org.apache.maven.artifact.repository.ArtifactRepository
* org.apache.maven.artifact.repository.ArtifactRepositoryPolicy
* org.apache.maven.artifact.repository.ArtifactRepositoryFactory
* org.apache.maven.artifact.repository.layout.ArtifactRepositoryLayout
* org.apache.maven.artifact.resolver.ArtifactResolver
* org.apache.maven.artifact.resolver.filter.ArtifactFilter
* org.apache.maven.artifact.resolver.filter.Artifact

h3. Unsupported Compatibility
* org.apache.maven.artifact.metadata.ArtifactMetadataSource
* org.apache.maven.artifact.metadata.ResolutionGroup
* org.apache.maven.artifact.repository.metadata.*
* org.apache.maven.artifact.resolver.ResolutionNode
* org.apache.maven.artifact.resolver.ResolutionListener
* org.apache.maven.artifact.resolver.metadata.*
* org.apache.maven.artifact.resolver.transform.*
* org.apache.maven.artifact.resolver.versioning.*

h2. Changes to the CLI
* Log file support has been added i.e mvn -l log.txt clean install
* Plugin registry option has not been supported in the core and it lagged around in the CLI