@Nonnull
    default String key() {
        return getGroupId()
                + ':'
                + getArtifactId()
                + ':'
                + getExtension()
                + (getClassifier().isEmpty() ? "" : ":" + getClassifier())
                + ':'
                + getVersion();
    }

    /**
     * The groupId of the artifact.
     *
     * @return the groupId
     */
    @Nonnull

        this.groupId = (groupId != null && !groupId.isEmpty()) ? groupId : null;
        this.artifactId = (artifactId != null && !artifactId.isEmpty()) ? artifactId : null;
        this.classifier = (classifier != null && !classifier.isEmpty()) ? classifier : null;
        this.extension = (extension != null && !extension.isEmpty()) ? extension : null;
        this.version = (version != null && !version.isEmpty()) ? version : null;

        this.key = getGroupId()
                + ':'
                + getArtifactId()
                + ':'
                + getExtension()
                + (getClassifier().isEmpty() ? "" : ":" + getClassifier())
                + ':'
                + getVersion();
    }

    public org.eclipse.aether.artifact.Artifact getArtifact() {
        return artifact;
    }

    @Override

            path.append(ARTIFACT_SEPARATOR).append(artifact.getClassifier());
        }

        if (artifactHandler.getExtension() != null
                && !artifactHandler.getExtension().isEmpty()) {
            path.append(GROUP_SEPARATOR).append(artifactHandler.getExtension());
        }

        return path.toString();
    }

        return ((groupId != null && !groupId.isEmpty()) ? groupId : "[unknown-group-id]")
                + ':'
                + ((artifactId != null && !artifactId.isEmpty()) ? artifactId : "[unknown-artifact-id]")
                + ':'
                + ((version != null && !version.isEmpty()) ? version : "[unknown-version]");
    }

    /**

    protected boolean isSiteEmpty(Site site) {
        return (site.getId() == null || site.getId().isEmpty())
                && (site.getName() == null || site.getName().isEmpty())
                && (site.getUrl() == null || site.getUrl().isEmpty());
    }

    @Override
    protected void mergeSite_Url(

        final Set<String> notFoundRequiredProfiles = requiredProfiles.stream()
                .filter(rap -> !allAvailableProfiles.contains(rap))
                .collect(toSet());

        if (!notFoundRequiredProfiles.isEmpty()) {
            // Use SLF4J formatter for consistency with warnings reported by logger
            final String message = MessageFormatter.format(

                List<Path> toLoad = new ArrayList<>();
                Path root = defaultModelBuilder.getModelProcessor().locateExistingPom(rootDirectory);
                toLoad.add(root);
                while (!toLoad.isEmpty()) {
                    Path pom = toLoad.remove(0);
                    try {
                        ModelBuilderRequest gaBuildingRequest =

        values.add(0, new ScopeState());
    }

    protected ScopeState getScopeState() {
        if (values.isEmpty()) {
            throw new OutOfScopeException("Cannot access session scope outside of a scoping block");
        }
        return values.get(0);
    }

    public void exit() {
        if (values.isEmpty()) {
            throw new IllegalStateException();
        }
        values.remove(0);
    }

                }

                Set<Artifact> directArtifacts = resolutionGroup.getArtifacts();

                if (artifacts == null || artifacts.isEmpty()) {
                    artifacts = directArtifacts;
                } else {
                    List<Artifact> allArtifacts = new ArrayList<>();
                    allArtifacts.addAll(artifacts);