*/
    ImmutableMultimap<String, HashCode> getRootHashes();

    boolean wasCreatedWithStrategy(FingerprintingStrategy strategy);

    FileCollectionFingerprint EMPTY = new FileCollectionFingerprint() {
        @Override
        public Map<String, FileSystemLocationFingerprint> getFingerprints() {
            return ImmutableSortedMap.of();
        }

        @Override

    }

    def canCreateEmptySnapshot() {
        TestFile file = tmpDir.createFile('file')

        when:
        FileCollectionFingerprint fingerprint = FileCollectionFingerprint.EMPTY
        FileCollectionFingerprint newFingerprint = fingerprinter.fingerprint(files(file))
        virtualFileSystem.invalidateAll()
        changes(fingerprint, newFingerprint, listener)

        then:
        fingerprint.fingerprints.isEmpty()

        def missingFile = file('some').createDir().file('does-not-exist')
        def missingRootFile = file('missing-root')

        when:
        def fileCollectionFingerprint = fingerprint(emptyDir.parentFile, missingFile.parentFile, missingRootFile)

        then:
        fileCollectionFingerprint.empty
    }

    def "root elements are unsorted, non-root elements are sorted amongst themselves"() {

import org.gradle.internal.fingerprint.CurrentFileCollectionFingerprint;
import org.gradle.internal.fingerprint.FileCollectionFingerprint;

public interface IncrementalInputProperties {
    String getPropertyNameFor(Object value);
    InputFileChanges nonIncrementalChanges(ImmutableSortedMap<String, FileCollectionFingerprint> previous, ImmutableSortedMap<String, CurrentFileCollectionFingerprint> current);

        .build();

    protected final SortedMap<String, FileCollectionFingerprint> previous;
    protected final SortedMap<String, CurrentFileCollectionFingerprint> current;
    private final String title;

    protected AbstractFingerprintChanges(SortedMap<String, FileCollectionFingerprint> previous, SortedMap<String, CurrentFileCollectionFingerprint> current, String title) {

import org.gradle.internal.fingerprint.FileCollectionFingerprint;

import java.util.SortedMap;

public class DefaultInputFileChanges extends AbstractFingerprintChanges implements InputFileChanges {
    private static final String TITLE = "Input";

    public DefaultInputFileChanges(SortedMap<String, FileCollectionFingerprint> previous, SortedMap<String, CurrentFileCollectionFingerprint> current) {

        this.hashCodeSerializer = new HashCodeSerializer();
    }

    @Override
    public FileCollectionFingerprint read(Decoder decoder) throws IOException {
        Map<String, FileSystemLocationFingerprint> fingerprints = fingerprintMapSerializer.read(decoder);
        if (fingerprints.isEmpty()) {
            return FileCollectionFingerprint.EMPTY;
        }
        ImmutableMultimap<String, HashCode> rootHashes = readRootHashes(decoder);

            writeValueSnapshot(encoder, entry.getValue());
        }
    }

    private ImmutableSortedMap<String, FileCollectionFingerprint> readFingerprints(Decoder decoder) throws Exception {
        int count = decoder.readSmallInt();
        ImmutableSortedMap.Builder<String, FileCollectionFingerprint> builder = ImmutableSortedMap.naturalOrder();
        for (int fingerprintIdx = 0; fingerprintIdx < count; fingerprintIdx++) {

     * Archive the file collection fingerprint.
     *
     * @return a file collection fingerprint which can be archived.
     */
    FileCollectionFingerprint archive(ArchivedFileCollectionFingerprintFactory factory);

    interface ArchivedFileCollectionFingerprintFactory {

 * limitations under the License.
 */

package org.gradle.internal.execution.history.changes;

import org.gradle.internal.fingerprint.FileCollectionFingerprint;

/**
 * Strategy to compare two {@link FileCollectionFingerprint}s.
 *
 * The strategy first tries to do a trivial comparison and delegates the more complex cases to a separate implementation.
 */
public interface FingerprintCompareStrategy {