@Optional @InputDirectory
    final DirectoryProperty inDir = project.objects.directoryProperty()

    @Optional @OutputFile
    final RegularFileProperty outFile = project.objects.fileProperty()

    @Optional @OutputDirectory
    final DirectoryProperty outDir = project.objects.directoryProperty()

    @TaskAction
    def go() { }
}

    }

    DefaultSourceDirectorySet(String name, String displayName, PatternSet patterns, PatternSet filters, TaskDependencyFactory taskDependencyFactory, FileCollectionFactory fileCollectionFactory, DirectoryFileTreeFactory directoryFileTreeFactory, DirectoryProperty destinationDirectory, DirectoryProperty classesDirectory) {

perty] and link:{javadocPath}/org/gradle/api/file/DirectoryProperty.html[DirectoryProperty]. link:{javadocPath}/org/gradle/api/model/ObjectFactory.html[ObjectFactory] has methods to create these: link:{javadocPath}/org/gradle/api/model/ObjectFactory.html#fileProperty--[ObjectFactory.fileProperty()] and link:{javadocPath}/org/gradle/api/model/ObjectFactory.html#directoryProperty--[ObjectFactory.directoryProperty()].

A `DirectoryProperty` can also be used to create a lazily evaluated `Provider`...

    private final ModularitySpec modularity;
    private final JavaToolchainSpec toolchain;
    private final ProjectInternal project;

    private final DirectoryProperty docsDir;
    private final DirectoryProperty testResultsDir;
    private final DirectoryProperty testReportDir;
    private JavaVersion srcCompat;
    private JavaVersion targetCompat;
    private boolean autoTargetJvm = true;

    @Inject

                abstract DirectoryProperty getOutputDir()

                @TaskAction
                void createOutput() {
                    outputDir.file("tracked.txt").get().asFile.text = "tracked"
                }
            }

            abstract class Consumer extends DefaultTask {
                @InputDirectory
                abstract DirectoryProperty getInputDir()

            abstract class MyTask extends DefaultTask {
                @Incremental
                @InputDirectory
                abstract DirectoryProperty getInputOne()

                @Incremental
                @InputDirectory
                abstract DirectoryProperty getInputTwo()

                @OutputDirectory
                File outputDirectory

                @TaskAction

            return new FixedDirectory(dir, dirResolver, fileCollectionFactory.withResolver(dirResolver));
        }
    }

    public static class DefaultDirectoryVar extends AbstractFileVar<Directory, DirectoryProperty> implements DirectoryProperty, Managed {
        private final FileResolver resolver;
        private final FileCollectionFactory fileCollectionFactory;

        "File = T extends FileSystemLocation"           | "DirectoryProperty"  | 'layout.buildDirectory.dir("out").get()' | "out"
        "File = Provider<T extends FileSystemLocation>" | "DirectoryProperty"  | 'layout.buildDirectory.dir("out")'       | "out"
        "File = File"                                   | "DirectoryProperty"  | 'file("$buildDir/out")'                  | "out"

 * limitations under the License.
 */

package org.gradle.language.swift.tasks;

import org.gradle.api.DefaultTask;
import org.gradle.api.file.ConfigurableFileCollection;
import org.gradle.api.file.DirectoryProperty;
import org.gradle.api.file.RegularFileProperty;
import org.gradle.api.model.ObjectFactory;
import org.gradle.api.provider.ListProperty;
import org.gradle.api.provider.Property;
import org.gradle.api.tasks.CacheableTask;

import groovy.lang.Closure;
import groovy.lang.DelegatesTo;
import org.gradle.api.Action;
import org.gradle.api.InvalidUserDataException;
import org.gradle.api.file.CopySpec;
import org.gradle.api.file.DirectoryProperty;
import org.gradle.api.file.DuplicatesStrategy;
import org.gradle.api.file.FileCopyDetails;
import org.gradle.api.internal.file.FileCollectionFactory;
import org.gradle.api.internal.file.copy.CopySpecInternal;