* same class realm is used to load build extensions and load mojos for extensions=true plugins.
     * </p>
     * <strong>Note:</strong> This is part of internal implementation and may be changed or removed without notice
     *
     * @since 3.3.0
     */
    public static final String KEY_EXTENSIONS_REALMS = DefaultMavenPluginManager.class.getName() + "/extensionsRealms";

     * @param extension the artifact extension, or {@code null} is unspecified
     * @return artifact with the given coordinates
     *
     * @see org.apache.maven.api.services.ArtifactFactory#create(Session, String, String, String, String)
     */
    @Nonnull
    Artifact createArtifact(String groupId, String artifactId, String version, String extension);

    /**

                session.createArtifactCoordinate("org.apache.maven.core.test", "test-extension", "1", "jar"));

        List<Path> paths = session.resolveDependencies(coord);

        assertNotNull(paths);
        assertEquals(10, paths.size());
        assertEquals("test-extension-1.jar", paths.get(0).getFileName().toString());

        String groupId = artifact.getGroupId();
        String artifactId = artifact.getArtifactId();
        String version = artifact.getBaseVersion();
        String classifier = artifact.getClassifier();
        String extension = artifact.getExtension();
        Path repo = getProjectLocalRepo();
        return repo.resolve(groupId)
                .resolve(artifactId)
                .resolve(version)
                .resolve(artifactId

META-INF/MANIFEST.MF Manifest-Version: 1.0 Archiver-Version: Plexus Archiver Created-By: Apache Maven Built-By: Brett Build-Jdk: 1.5.0_04 Extension-Name: maven-plugin-api Specification-Title: Maven is a project development management and com prehension tool. Based on the concept of a project object model: buil ds, dependency management, documentation creation, site publication, and distribution publication are all controlled from the declarative file. Maven can be extended by plugins to utilise...

            mergePlugin_ArtifactId(builder, target, source, sourceDominant, context);
            mergePlugin_Version(builder, target, source, sourceDominant, context);
            mergePlugin_Extensions(builder, target, source, sourceDominant, context);
            mergePlugin_Executions(builder, target, source, sourceDominant, context);
            mergePlugin_Dependencies(builder, target, source, sourceDominant, context);

              <goal>xdoc</goal>
            </goals>
            <phase>pre-site</phase>
            <configuration>
              <version>1.0.0</version>
              <models>
                <model>src/main/mdo/extension.mdo</model>
              </models>
            </configuration>
          </execution>
        </executions>
      </plugin>
      <plugin>
        <groupId>org.codehaus.mojo</groupId>

import org.apache.maven.api.model.DeploymentRepository;
import org.apache.maven.api.model.DistributionManagement;
import org.apache.maven.api.model.Exclusion;
import org.apache.maven.api.model.Extension;
import org.apache.maven.api.model.InputLocation;
import org.apache.maven.api.model.IssueManagement;
import org.apache.maven.api.model.Model;
import org.apache.maven.api.model.ModelBase;

        }
        return artifactGeneratorFactories;
    }

    protected Map<String, ArtifactGeneratorFactory> createArtifactGeneratorFactories() {
        // by default none, this is extension point
        return new HashMap<>();
    }

    private Map<String, ArtifactDecoratorFactory> artifactDecoratorFactories;

    public final Map<String, ArtifactDecoratorFactory> getArtifactDecoratorFactories() {

            infos.put(dstKey, srcInfo);
        }
    }

    private String getKey(String classifier, String extension) {
        return (classifier == null ? "" : classifier.trim()) + ':' + (extension == null ? "" : extension.trim());
    }

    private ArtifactRepository getRepository(