final Optional<FileTree> testFileTree = getJavaTestSourceSet(project).map(SourceSet::getResources).map(FileTree::getAsFileTree);
        final Optional<FileTree> mainFileTree = getJavaMainSourceSet(project).map(SourceSet::getResources).map(FileTree::getAsFileTree);
        if (testFileTree.isPresent() && mainFileTree.isPresent()) {
            return testFileTree.get().plus(mainFileTree.get()).matching(filter);

    private FileCollection config;
    private FileCollection additionalConfig;
    private Function<FileCollection, FileTree> configToFileTree = FileCollection::getAsFileTree;
    private Function<FileCollection, FileTree> additionalConfigToFileTree = FileCollection::getAsFileTree;

    private final PatternFilterable patternSet;
    private final ProjectLayout projectLayout;
    private final FileSystemOperations fileSystemOperations;

    private FileCollection additionalConfig;
    private Function<FileCollection, FileTree> coreConfigToFileTree = FileCollection::getAsFileTree;
    private Function<FileCollection, FileTree> xpackConfigToFileTree = FileCollection::getAsFileTree;
    private Function<FileCollection, FileTree> additionalConfigToFileTree = FileCollection::getAsFileTree;

    private final PatternFilterable corePatternSet;
    private final PatternFilterable xpackPatternSet;

            f.include(PublicApi.INSTANCE.getIncludes());
            // Filter out any non-public APIs
            f.exclude(PublicApi.INSTANCE.getExcludes());
        }));
        extension.getKotlinDslSource().from(sourcesPath.getIncoming().artifactView(v -> v.lenient(true)).getFiles().getAsFileTree().matching(f -> {

        getFs().delete(spec -> spec.delete(destinationDirectory));
        destinationDirectory.mkdirs();

        Path adocDir = getDocumentationRoot().get().getAsFile().toPath();
        getDocumentationFiles().getAsFileTree().matching(pattern -> pattern.include("**/*.adoc")).forEach(adocFile -> {
            String adocFileName = adocFile.getName();
            // getting_started.adoc -> getting_started-docinfo.html

        final Version version = VersionProperties.getElasticsearchVersion();

        final FileTree yamlFiles = projectDirectory.dir("docs/changelog")
            .getAsFileTree()
            .matching(new PatternSet().include("**/*.yml", "**/*.yaml"));

        final Provider<ValidateYamlAgainstSchemaTask> validateChangelogsAgainstYamlTask = project.getTasks()

        return getSourceFolders().get()
            .stream()
            .map(sourceFolder -> sourceFolder.matching(filesFilter))
            .reduce(FileTree::plus)
            .orElse(projectLayout.files().getAsFileTree());
    }

    @TaskAction
    public void checkInvalidPatterns() throws IOException {
        Pattern allPatterns = Pattern.compile("(" + String.join(")|(", getPatterns().values()) + ")");

        return getSources().get()
            .stream()
            .map(sourceTree -> sourceTree.matching(filesFilter))
            .reduce(FileTree::plus)
            .orElse(projectLayout.files().getAsFileTree());
    }

    @TaskAction
    public void checkInvalidPermissions() throws IOException {
        if (Os.isFamily(Os.FAMILY_WINDOWS)) {
            throw new StopExecutionException();
        }

    @TaskAction
    public void checkMissingFiles() {
        String directoryPath = getDocumentationRoot().get().toString();
        FileCollection jsonFiles = getJsonFilesDirectory().getAsFileTree().filter(file -> file.getName().endsWith(".json"));

        try {
            List<String> allErrors = new ArrayList<>();
            Set<String> allExistingAnchors = findAllAdocAnchors(directoryPath);

    public abstract DirectoryProperty getDocumentationRoot();

    @TaskAction
    public void checkMultiLanguageSnippets() {
        Map<File, List<Error>> errors = new TreeMap<>();

        getDocumentationRoot().getAsFileTree().matching(spec -> spec.include("**/*.adoc")).forEach(file -> {
            gatherBadSnippetsInFile(file, errors);
        });

        if (!errors.isEmpty()) {