def "cannot mutate outgoing variants after configuration is resolved"() {
        given:
        buildFile << """

        configurations {
            compile {
                attributes.attribute(usage, 'for compile')
                outgoing {
                    artifact file('lib1.jar')
                    variants {
                        classes {

        def childPublication = publication(childComponent, child1)

        def variant = Stub(UsageContext)
        variant.name >> "v1"
        variant.attributes >> attributes(usage: "compile")

        rootComponent.variants >> [childComponent]
        rootComponent.usages >> []
        childComponent.usages >> [variant]

        when:
        writeTo(writer, childPublication, [rootPublication, childPublication])

     */
    @Nullable
    Identifier getIdentifier();

    DisplayName asDescribable();

    @Override
    ImmutableAttributes getAttributes();

    ImmutableList<? extends ComponentArtifactMetadata> getArtifacts();

    @Override
    ImmutableCapabilities getCapabilities();

    boolean isExternalVariant();

    /**
     * Is this variant eligible for caching?
     *

@HasInternalProtocol
public interface VersionMappingStrategy {
    /**
     * Configures the version mapping strategy for all variants
     * @param action the configuration action
     */
    void allVariants(Action<? super VariantVersionMappingStrategy> action);

    /**
     * Configures the version mapping strategy for the variant which matches the provided
     * attribute value.
     * @param attribute the attribute to find

The following rules are enforced:

* Variant names must be unique,
* Each variant must have at least <<variant_attributes.adoc#variant_attributes,one attribute>>,
* Two variants cannot have the <<variant_model.adoc#understanding-variant-selection,exact same attributes and capabilities>>,
* If there are dependencies, at least one, across all variants, must carry <<rich_versions.adoc#rich-version-constraints,version information>>.

        super.assertPublished()

        // Verify Gradle metadata particulars
        assert mavenModule.parsedModuleMetadata.variants*.name as Set == ['apiElements', 'runtimeElements'] as Set
        assert mavenModule.parsedModuleMetadata.variant('apiElements').files.empty
        assert mavenModule.parsedModuleMetadata.variant('runtimeElements').files.empty

        // Verify POM particulars
        assert mavenModule.parsedPom.packaging == 'pom'

        boolean isExternalVariant
    ) {
        NameOnlyVariantResolveMetadata variant = new NameOnlyVariantResolveMetadata(configurationName);
        ImmutableAttributes variantAttributes = variantMetadataRules.applyVariantAttributeRules(variant, attributes);
        ImmutableCapabilities variantCapabilities = variantMetadataRules.applyCapabilitiesRules(variant, capabilities);

            type = "other"
        }
        String variants = result.variants.collect { variant ->
            "variant:${formatVariant(variant)}"
        }.join('@@')
        "[$type][id:${result.id}][mv:${result.moduleVersion}][reason:${formatReason(result.selectionReason as ComponentSelectionReasonInternal)}][$variants]"
    }

    protected String formatVariant(ResolvedVariantResult variant) {

 *
 * <p>Features are classified by their capabilities. Each variant of a feature provides at least
 * the same set of capabilities as the feature itself. Since all variants of a feature are derived
 * from the same sources, they all expose the same API or "content" and thus provide the same
 * capabilities. Some variants may expose additional capabilities than those of its owning feature,
 * for example with fat jars.</p>

public interface GraphSelectionCandidates {

    /**
     * Returns the set of variants to select from during attribute matching, or an empty list of this
     * component does not support attribute matching.
     */
    List<? extends VariantGraphResolveState> getVariantsForAttributeMatching();

    /**
     * Returns the variant to use when attribute-based variant selection is not enabled.
     */
    @Nullable