*/
public interface ValueSnapshot extends Hashable {
    /**
     * Takes a snapshot of the given value, using this as a candidate snapshot. If the value is the same as the value represented by this snapshot, this snapshot must be returned.
     */
    ValueSnapshot snapshot(@Nullable Object value, ValueSnapshotter snapshotter);

        when:
        source "class A { /* change */ }"
        run language.compileTaskName

        then:
        outputs.recompiledClasses 'A', 'B', 'C'

        when:
        outputs.snapshot()
        source "class B { /* change */ }"
        run language.compileTaskName

        then:
        outputs.recompiledClasses 'B', 'C'
    }

        """
    }

    @ToBeFixedForConfigurationCache
    def "rebuilds executable with single source file change"() {
        given:
        run installApp
        libObjects.snapshot()
        appObjects.snapshot()

        when:
        appSourceFile.replace("world", "planet")

        and:
        run installApp

        then:

        return super.hashCode() ^ className.hashCode();
    }

    @Override
    public ValueSnapshot snapshot(Object value, ValueSnapshotter snapshotter) {
        ValueSnapshot snapshot = snapshotter.snapshot(value);
        if (snapshot.equals(this)) {
            return this;
        }
        return snapshot;
    }

    @Override
    public String toString() {
        return "(" + className + ") " + state;
    }

        snapshotSources.expectHead()
        snapshotSources.expectGet()

        then:
        checkArtifactsResolvedAndCached()

        when:
        def snapshot = file("sources/some-artifact-1.0-SNAPSHOT-sources.jar").snapshot()
        snapshotModule.publishWithChangedContent()
        fixture.withSnapshotTimestamp(snapshotModule.uniqueSnapshotVersion)
                .createVerifyTask("verifyRefresh")

        "1.0-rc"       | "1.0-sp"
        "1.0-rc"       | "1.0"
        "1.0-rc-1"     | "1.0"

        "1.0-snapshot" | "1.0-final"
        "1.0-snapshot" | "1.0-ga"
        "1.0-snapshot" | "1.0-release"
        "1.0-snapshot" | "1.0-sp"
        "1.0-snapshot" | "1.0"

        "1.0-final"    | "1.0-ga"
        "1.0-final"    | "1.0-release"
        "1.0-final"    | "1.0-sp"

import org.gradle.internal.snapshot.impl.IsolatedManagedValue
import org.gradle.internal.snapshot.impl.IsolatedMap
import org.gradle.internal.snapshot.impl.IsolatedJavaSerializedValueSnapshot
import org.gradle.internal.snapshot.impl.IsolatedSet
import org.gradle.internal.snapshot.impl.MapEntrySnapshot
import org.gradle.internal.snapshot.impl.NullValueSnapshot
import org.gradle.internal.snapshot.impl.StringValueSnapshot

     * default behavior is to fingerprint directories, for others, they ignore directories by default.
     */
    DEFAULT(snapshot -> true),
    /**
     * Ignore directories
     */
    IGNORE_DIRECTORIES(snapshot -> snapshot.getType() != FileType.Directory);

    @SuppressWarnings("ImmutableEnumChecker")
    private final Predicate<FileSystemLocationSnapshot> fingerprintCheck;

        TrackingProperties(System.getProperties().uncheckedCast()) { prefix, snapshot ->
            listener.systemPropertiesPrefixedBy(prefix, snapshot)
        }

    override fun getVariables(): Environment.Properties =
        TrackingProperties(System.getenv()) { prefix, snapshot ->
            listener.envVariablesPrefixedBy(prefix, snapshot)
        }

    private
    class TrackingProperties(

        }
        return snapshot;
    }

    private void collectEntry(FileSystemLocationSnapshot snapshot) {
        Directory directory = directoryStack.peekLast();
        if (directory != null) {
            directory.collectEntry(snapshot);
        } else {
            assert result == null;
            result = snapshot;
        }
    }

    @Override