Set<Attribute<?>> extraAttributes = new LinkedHashSet<>();
        for (ImmutableAttributes attributes : candidateAttributeSets) {
            extraAttributes.addAll(attributes.keySet());
        }
        removeSameAttributes(requested, extraAttributes);
        Attribute<?>[] extraAttributesArray = extraAttributes.toArray(new Attribute<?>[0]);

    }

    @Override
    public ImmutableMap<NamespaceId, String> getExtraAttributes() {
        return extraAttributes;
    }

    @Override
    public void setExtraAttributes(Map<NamespaceId, String> extraAttributes) {
        this.extraAttributes = ImmutableMap.copyOf(extraAttributes);
    }

    @Nullable
    @Override
    public String getBranch() {
        return branch;
    }

        ]
        AttributeContainer requested = attribute(attr1, "v3")

        when:
        def extraAttributes = schema.collectExtraAttributes(candidates, requested).toList()

        then:
        extraAttributes.contains(attr2)
        extraAttributes.contains(attr3)
        !extraAttributes.contains(attr1)
    }

    def "prefers extra attributes from the selection schema"() {

        requested {
            attribute(attr1, "v3")
        }

        when:
        collectExtraAttributes()

        then:
        extraAttributes.isEmpty()
    }

    private boolean hasExtraAttribute(Attribute<?> attribute) {
        extraAttributes.contains(attribute)
    }

    private boolean doesNotHaveExtraAttribute(Attribute<?> attribute) {
        !hasExtraAttribute(attribute)
    }

        return createModuleRevisionId(org, name, branch, rev, extraAttributes, true);
    }

    public static ModuleRevisionId createModuleRevisionId(String org, String name, String branch, String revConstraint, Map<String, String> extraAttributes, boolean replaceNullBranchWithDefault) {
        synchronized (MODULE_ID_LOCK) {

        this.branch = metadata.branch;
        this.artifactDefinitions = metadata.artifactDefinitions;
        this.dependencies = metadata.dependencies;
        this.excludes = metadata.excludes;
        this.extraAttributes = metadata.extraAttributes;

        copyCachedState(metadata, metadata.getVariantDerivationStrategy() != variantDerivationStrategy);
    }

        this.prefix = prefix
        this.server = server
        this.backingModule = backingModule
    }

    IvyHttpModule withExtraAttributes(Map extraAttributes) {
        backingModule.withExtraAttributes(extraAttributes)
        return this
    }

    IvyHttpModule withExtraInfo(Map extraInfo) {
        backingModule.withExtraInfo(extraInfo)
        return this
    }

        Map<NamespaceId, String> extraAttributes = converter.extractExtraAttributes(ivyDescriptor);
        MutableIvyModuleResolveMetadata metadata = metadataFactory.create(cid, dependencies, configurations, artifacts, excludes);
        metadata.setStatus(ivyDescriptor.getStatus());
        metadata.setExtraAttributes(extraAttributes);
        metadata.setBranch(ivyDescriptor.getModuleRevisionId().getBranch());

     * Returns the Ivy excludes of this component.
     */
    ImmutableList<Exclude> getExcludes();

    ImmutableMap<NamespaceId, String> getExtraAttributes();

    void setExtraAttributes(Map<NamespaceId, String> extraAttributes);

    @Nullable
    String getBranch();

    void setBranch(@Nullable String branch);