}

    @Override
    public List<MavenProject> getDownstreamProjects(MavenProject project, boolean transitive) {
        Objects.requireNonNull(project, "project cannot be null");

        Set<String> projectIds = new HashSet<>();

        getDownstreamProjects(ProjectSorter.getId(project), projectIds, transitive);

        return getSortedProjects(projectIds);
    }

        when(projectDependencyGraph.getDownstreamProjects(bProject, transitive)).thenReturn(List.of(cProject));

        graph.getDownstreamProjects(bProject, transitive);
        graph.getDownstreamProjects(bProject, transitive);

        verify(projectDependencyGraph).getDownstreamProjects(bProject, transitive);
    }

    @ParameterizedTest

        assertEquals(aProject, sortedProjects.get(0));
        assertEquals(cProject, sortedProjects.get(1));

        assertTrue(graph.getDownstreamProjects(aProject, false).contains(cProject));
    }

    // Test verifying that getDownstreamProjects does not contain duplicates.
    // This is a regression test for https://github.com/apache/maven/issues/2487.
    //
    // The graph is:
    // aProject -> bProject

    }

    @Override
    public List<MavenProject> getSortedProjects() {
        return new ArrayList<>(sortedProjects);
    }

    @Override
    public List<MavenProject> getDownstreamProjects(MavenProject project, boolean transitive) {
        Key key = new Key(project, transitive, false);
        // Do not use computeIfAbsent here, as the computation is recursive

    public void blackList(MavenProject project) {
        if (blackListedProjects.add(BuilderCommon.getKey(project)) && projectDependencyGraph != null) {
            for (MavenProject downstreamProject : projectDependencyGraph.getDownstreamProjects(project, true)) {
                blackListedProjects.add(BuilderCommon.getKey(downstreamProject));
            }
        }
    }

    public void halt() {
        halted = true;
    }

     *            downstream projects.
     * @return The downstream projects in the build order, never {@code null}.
     */
    List<MavenProject> getDownstreamProjects(MavenProject project, boolean transitive);

    /**
     * Gets the upstream projects of the specified project. An upstream project is a project that directly or indirectly
     * is a prerequisite of the given project.

        List<MavenProject> result = new ArrayList<>();
        // schedule dependent projects, if all of their requirements are met
        for (MavenProject dependentProject : projectDependencyGraph.getDownstreamProjects(finishedProject, false)) {
            final List<MavenProject> upstreamProjects =
                    projectDependencyGraph.getUpstreamProjects(dependentProject, false);

    public List<MavenProject> getSortedProjects() {
        return Arrays.asList(A, B, C, X, Y, Z); // I'm not entirely sure about the order but this should do...
    }

    @Override
    public List<MavenProject> getDownstreamProjects(MavenProject project, boolean transitive) {
        if (transitive) {
            throw new RuntimeException("Not implemented yet");
        }
        List<MavenProject> result = new ArrayList<>();

    }

    private long calculateWeight(MavenProject project) {
        // Calculate maximum weight of downstream dependencies
        long maxDownstreamWeight = dependencyGraph.getDownstreamProjects(project, false).stream()
                .mapToLong(this::getProjectWeight)
                .max()
                .orElse(0L);

        // Weight = 1 + max downstream weight (similar to Takari Smart Builder)

                if (makeUpstream) {
                    projectsSet.addAll(graph.getUpstreamProjects(project, true));
                }
                if (makeDownstream) {
                    projectsSet.addAll(graph.getDownstreamProjects(project, true));
                }
            }

            result = new ArrayList<>(projectsSet);

            // Order the new list in the original order