import org.gradle.util.internal.GUtil;

import java.io.File;
import java.util.Set;

/**
 * Adapts a java util collection into a file set.
 */
public class ListBackedFileSet implements MinimalFileSet {
    private final ImmutableSet<File> files;

    public ListBackedFileSet(ImmutableSet<File> files) {
        this.files = files;
    }

    @Override
    public String getDisplayName() {
        switch (files.size()) {

        def testFile = new File('test-file')
        def testFile2 = new File('test-file2')

        expect:
        new ListBackedFileSet(ImmutableSet.of()).displayName == "empty file collection"
        new ListBackedFileSet(ImmutableSet.of(testFile)).displayName == "file '$testFile'"
        new ListBackedFileSet(ImmutableSet.of(testFile, testFile2)).displayName == "files '$testFile', '$testFile2'"
    }

    void containsSpecifiedFiles() {

import org.gradle.api.internal.file.collections.DefaultConfigurableFileCollection;
import org.gradle.api.internal.file.collections.FileCollectionAdapter;
import org.gradle.api.internal.file.collections.ListBackedFileSet;
import org.gradle.api.internal.provider.PropertyHost;
import org.gradle.api.internal.tasks.TaskDependencyFactory;
import org.gradle.api.internal.tasks.properties.LifecycleAwareValue;

                ImmutableSet<File> files = ImmutableSet.copyOf(contents);
                if (!files.isEmpty()) {
                    builder.add(new FileCollectionAdapter(new ListBackedFileSet(files), taskDependencyFactory, patternSetFactory));
                }
            }

            @Override
            public void visitFileTree(File root, PatternSet patterns, FileTreeInternal fileTree) {