project.getFile(),
                        "Project '" + projectId + "' is duplicated in the reactor");
            }

            String projectKey = ArtifactUtils.versionlessKey(project.getGroupId(), project.getArtifactId());

            Map<String, Vertex> vertices = vertexMap.computeIfAbsent(projectKey, k -> new HashMap<>(2, 1));

    }

    public void setDependencyNode(DependencyNode dependencyNode) {
        this.dependencyNode = dependencyNode;
    }

    /**
     * The map of artifacts accessible by the versionlessKey, i.e. groupId:artifactId
     *
     * @return a Map of artifacts, never {@code null}
     * @see #getArtifacts()
     */
    public Map<String, Artifact> getArtifactMap() {
        if (artifactMap == null) {

        assertNotNull(depResults);
        assertEquals(1, depResults.size());
        assertSame(
                depArtifact,
                depResults.get(ArtifactUtils.versionlessKey(depArtifact)),
                "dependency artifact is wrong.");
    }

    @Test
    void testPluginArtifactIdExpressionReference() throws Exception {
        MojoExecution exec = newMojoExecution();