private final ImmutableList<FileCollectionInternal> fileCollections;

        public ResolvedItemsCollector(ImmutableList<FileCollectionInternal> fileCollections) {
            this.fileCollections = fileCollections;
        }

        @Override
        public boolean isEmpty() {
            return fileCollections.isEmpty();
        }

        @Override

        "FileCollection += FileCollection" | "+="      | "FileCollection" | 'files("a.txt")'  | '[a.txt]'
        "FileCollection << FileCollection" | "<<"      | "FileCollection" | 'files("a.txt")'  | unsupportedWithCause("No signature of method")

        'FileCollection'             | 'array'          | 'project.layout.files([ "src/resource/file.txt" ] as Object[])'
        'FileCollection'             | 'FileCollection' | "project.layout.files(project.layout.files('src/resource/file.txt'))"
        'FileCollection'             | 'Callable'       | "project.layout.files($STRING_CALLABLE)"

        when (fileCollection) {
            is SubtractingFileCollection -> {
                // TODO - when left and right are both static then we should serialize the current contents of the collection
                elements.add(SubtractingFileCollectionSpec(fileCollection.left, fileCollection.right))
                false
            }

                return sourceSet instanceof WindowsResourceSet;
            }
        };
        Transformer<FileCollection, LanguageSourceSet> transform = new Transformer<FileCollection, LanguageSourceSet>() {
            @Override
            public FileCollection transform(LanguageSourceSet sourceSet) {
                return sourceSet.getSource();
            }
        };

        TestFile file = root.createFile('file')
        def fileCollection = files(root)

        when:
        FileCollectionFingerprint fingerprint = fingerprinter.fingerprint(fileCollection)
        file.delete()
        file.createDir()
        virtualFileSystem.invalidateAll()
        changes(fingerprint, fingerprinter.fingerprint(fileCollection), listener)

        then:
        1 * listener.changed(file.path)

/**
 * See [Configuration.fileCollection].
 */
@Suppress("DEPRECATION")
@Deprecated(deprecationMessage, replaceWith = ReplaceWith("get().fileCollection(dependencySpec)"), level = DeprecationLevel.HIDDEN)
fun <T : Configuration> NamedDomainObjectProvider<T>.fileCollection(dependencySpec: Spec<Dependency>): FileCollection =
    get().fileCollection(dependencySpec)


/**

    @ToBeFixedForConfigurationCache(because = "Transform nodes are not serialized when transform of project artifact is not declared as a dependency of another node")
    def "task can query FileCollection containing the output of transform of project artifacts without declaring this access"() {
        setupBuildWithProjectArtifactTransforms()
        taskQueriesFilesWithoutDeclaringInput()

        when:

            return new OutputFileValueSupplier(fileCollection) {
                @Nonnull
                @Override
                public File getValue() {
                    return root;
                }
            };
        }

        public static OutputFileValueSupplier fromSupplier(Supplier<File> root, FileCollection fileCollection) {

    }

    private static class FileCollectionElementsFactory implements Factory<Set<FileSystemLocation>> {

        private final FileCollection fileCollection;

        private FileCollectionElementsFactory(FileCollection fileCollection) {
            this.fileCollection = fileCollection;
        }

        @Override
        public Set<FileSystemLocation> create() {