return result;
    }

    private static boolean artifactEquals(Artifact a1, Artifact a2) {
        if (a1 == a2) {
            return true;
        }

        return Objects.equals(a1.getGroupId(), a2.getGroupId())
                && Objects.equals(a1.getArtifactId(), a2.getArtifactId())
                && Objects.equals(a1.getType(), a2.getType())
                && Objects.equals(a1.getVersion(), a2.getVersion())

                .map(Dependency::getArtifact)
                .filter(d -> "org.apache.maven".equals(d.getGroupId()))
                .filter(d -> !DefaultPluginValidationManager.EXPECTED_PROVIDED_SCOPE_EXCLUSIONS_GA.contains(
                        d.getGroupId() + ":" + d.getArtifactId()))
                .map(Artifact::getVersion)
                .collect(Collectors.toSet());

    public PluginNotFoundException(Plugin plugin, ArtifactNotFoundException e) {
        super(
                "Plugin could not be found - check that the goal name is correct: " + e.getMessage(),
                e.getGroupId(),
                e.getArtifactId(),
                e.getVersion(),
                "maven-plugin",
                null,
                e.getRemoteRepositories(),
                null,

                return step.name + "(" + step.project.getGroupId() + ":" + artifactId + ")";
            } else {
                return step.name + "(:" + artifactId + ")";
            }
        }
    }

    protected void mojo(Consumer<String> writer, MojoExecution mojoExecution) {
        String mojoExecId =
                mojoExecution.getGroupId() + ':' + mojoExecution.getArtifactId() + ':' + mojoExecution.getVersion()

        buffer.append(" {execution: ").append(executionId).append('}');
        return buffer.toString();
    }

    public String getGroupId() {
        if (mojoDescriptor != null) {
            return mojoDescriptor.getPluginDescriptor().getGroupId();
        }

        return plugin.getGroupId();
    }

    public String getArtifactId() {
        if (mojoDescriptor != null) {

    }

    protected static Metadata createMetadata(Artifact artifact, Versioning versioning) {
        Metadata metadata = new Metadata();
        metadata.setGroupId(artifact.getGroupId());
        metadata.setArtifactId(artifact.getArtifactId());
        metadata.setVersion(artifact.getVersion());
        metadata.setVersioning(versioning);
        return metadata;
    }

    /**
     * Gets the effective group identifier of the model.
     *
     * @return The effective group identifier of the model or an empty string if unknown, never {@code null}.
     */
    public String getGroupId() {
        return (groupId != null) ? groupId : "";
    }

    /**
     * Sets the effective group identifier of the model.
     *

        Artifact artifact = mock(Artifact.class);
        when(artifact.getFile()).thenReturn(new File(new File("local/repository"), "some/path"));
        when(artifact.getGroupId()).thenReturn("group1");
        when(artifact.getArtifactId()).thenReturn("artifact1");
        when(artifact.getExtension()).thenReturn("ext");
        when(artifact.getClassifier()).thenReturn("classifier1");

        TaskProvider<RenderMarkdown> releaseNotesMarkdown = tasks.register("releaseNotesMarkdown", RenderMarkdown.class, task -> {
            task.setGroup("release notes");
            task.setDescription("Generate release notes HTML page from Markdown.");

            task.getInputEncoding().convention(Charset.defaultCharset().name());

                }
            }
        }
        return version;
    }

    public static String versionlessKey(Artifact artifact) {
        return versionlessKey(artifact.getGroupId(), artifact.getArtifactId());
    }

    public static String versionlessKey(String groupId, String artifactId) {
        notBlank(groupId, "groupId can neither be null, empty nor blank");