*
 */
public class DuplicateProjectException extends Exception {
    private final String projectId;

    private final File existingProjectFile;

    private final File conflictingProjectFile;

    /**
     * @deprecated use {@link #DuplicateProjectException(String, File, File, String)}
     */
    @Deprecated
    public DuplicateProjectException(String message) {

import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

/**
 * Signals a collision of two or more projects with the same g:a:v during a reactor build.
 *
 */
public class DuplicateProjectException extends MavenExecutionException {

    private Map<String, List<File>> collisions;

    /**
     * Creates a new exception with specified details.
     *

     *
     * @param projects The projects to create the dependency graph with
     * @throws DuplicateProjectException
     * @throws CycleDetectedException
     */
    public DefaultProjectDependencyGraph(Collection<MavenProject> projects)
            throws CycleDetectedException, DuplicateProjectException {
        this(projects, projects);
    }

    /**

import java.util.List;

import org.apache.maven.execution.ProjectDependencyGraph;
import org.apache.maven.model.Dependency;
import org.apache.maven.project.CycleDetectedException;
import org.apache.maven.project.DuplicateProjectException;
import org.apache.maven.project.MavenProject;
import org.junit.jupiter.api.Test;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertTrue;

/**

import java.util.Map;

import org.apache.maven.artifact.ArtifactUtils;
import org.apache.maven.plugin.descriptor.PluginDescriptor;
import org.apache.maven.project.CycleDetectedException;
import org.apache.maven.project.DuplicateProjectException;
import org.apache.maven.project.MavenProject;
import org.apache.maven.project.ProjectSorter;

/**
 * ReactorManager - unused
 */
@Deprecated
public class ReactorManager {

import org.apache.maven.model.building.DefaultModelProblem;
import org.apache.maven.model.building.Result;
import org.apache.maven.project.CycleDetectedException;
import org.apache.maven.project.DuplicateProjectException;
import org.apache.maven.project.MavenProject;
import org.apache.maven.project.ProjectBuildingException;
import org.apache.maven.project.collector.MultiModuleCollectionStrategy;

     * we are trying to build. we assume a closed set.</li>
     * <li>do a topo sort on the graph that remains.</li>
     * </ul>
     * @throws DuplicateProjectException if any projects are duplicated by id
     */
    // MAVENAPI FIXME: the DAG used is NOT only used to represent the dependency relation,
    // but also for <parent>, <build><plugin>, <reports>. We need multiple DAG's

import org.apache.maven.plugin.descriptor.MojoDescriptor;
import org.apache.maven.plugin.descriptor.PluginDescriptor;
import org.apache.maven.project.CycleDetectedException;
import org.apache.maven.project.DuplicateProjectException;
import org.apache.maven.project.MavenProject;
import org.codehaus.plexus.MutablePlexusContainer;
import org.codehaus.plexus.PlexusContainer;

import org.apache.maven.plugin.descriptor.MojoDescriptor;
import org.apache.maven.plugin.descriptor.PluginDescriptor;
import org.apache.maven.project.CycleDetectedException;
import org.apache.maven.project.DuplicateProjectException;
import org.apache.maven.project.MavenProject;
import org.codehaus.plexus.MutablePlexusContainer;
import org.codehaus.plexus.PlexusContainer;

        projects.add(project1);
        MavenProject project2 = createProject("groupId", "artifactId", "1.0");
        projects.add(project2);

        assertThrows(
                DuplicateProjectException.class,
                () -> new ProjectSorter(projects).getSortedProjects(),
                "Duplicate projects should fail");
    }

    @Test