import org.eclipse.aether.deployment.DeployRequest;
import org.eclipse.aether.impl.MetadataGenerator;
import org.eclipse.aether.impl.MetadataGeneratorFactory;
import org.eclipse.aether.installation.InstallRequest;

/**
 * Maven GA level metadata generator factory.
 */
@Named(VersionsMetadataGeneratorFactory.NAME)
@Singleton
public class VersionsMetadataGeneratorFactory implements MetadataGeneratorFactory {

import org.apache.maven.api.metadata.Metadata;
import org.apache.maven.api.metadata.Versioning;
import org.eclipse.aether.artifact.Artifact;
import org.eclipse.aether.artifact.ArtifactProperties;

/**
 * Maven GA level metadata.
 */
final class VersionsMetadata extends MavenMetadata {

    private final Artifact artifact;

    VersionsMetadata(Artifact artifact, Date timestamp) {

     * @param groupId    the groupId
     * @param artifactId the artifactId
     * @return the model, otherwise {@code null}
     * @throws IllegalStateException if multiple versions of the same GA are part of the reactor
     */
    Model getRawModel(Path from, String groupId, String artifactId);

    /**
     * Locate the POM file inside the given directory.
     */
    Path locate(Path path);

    private final Map<GAKey, Set<Model>> modelsByGa = new ConcurrentHashMap<>();

    private final Map<Path, Model> modelsByPath = new ConcurrentHashMap<>();

    /**
     * Get the model by its GAV or (since 4.0.0) by its GA if there is only one.
     *
     * @param groupId never {@code null}
     * @param artifactId never {@code null}
     * @param version can be {@code null}
     * @return the matching model or {@code null}

import org.eclipse.aether.installation.InstallRequest;
import org.eclipse.aether.metadata.Metadata;
import org.eclipse.aether.util.ConfigUtils;

/**
 * Maven GA level metadata generator.
 *
 * Version metadata contains list of existing baseVersions within this GA.
 */
class VersionsMetadataGenerator implements MetadataGenerator {

    private final Map<Object, VersionsMetadata> versions;