checkNotNull(valueComparator);
    return Comparator.<Optional<T>, @Nullable T>comparing(
        o -> orElseNull(o), Comparator.nullsLast(valueComparator));
  }

  // For discussion of why this exists, see the Android flavor.
  private static <T> @Nullable T orElseNull(Optional<T> optional) {
    return optional.orElse(null);
  }

  /**

import java.util.Arrays;
import java.util.Optional;

import org.junit.jupiter.api.DisplayName;
import org.junit.jupiter.api.Test;

/**
 * Tests for {@link DosError}.  Since {@link DosError} only contains
 * constants, the tests exercise the data and small helper logic in this
 * test class.
 */
public class DosErrorTest {
    private static Optional<Integer> findNtStatus(int dosErrorCode) {

     *
     * @param dir the directory to locate the pom for, never {@code null}
     * @return a {@code Source} pointing to the located pom or an empty {@code Optional} if none was found by this parser
     */
    @Nonnull
    Optional<Source> locate(@Nonnull Path dir);

    /**
     * Parse the model obtained previously by a previous call to {@link #locate(Path)}.
     *

     *
     * @return the optional POM file
     */
    @Nonnull
    Optional<Path> getPomFile();

    /**
     * Gets the project that was built.
     *
     * @return The project that was built or {@code null} if an error occurred and this result accompanies a
     *         {@link ProjectBuilderException}.
     */
    @Nonnull
    Optional<Project> getProject();

    /**

            VersionRange versionRange,
            String type,
            String classifier,
            String scope,
            boolean optional) {
        return createArtifact(groupId, artifactId, versionRange, type, classifier, scope, null, optional);
    }

    @Override
    public Artifact createDependencyArtifact(
            String groupId,
            String artifactId,

# Apache Maven Encrypt Script
#
# Environment Variable Prerequisites
#
#   JAVA_HOME           (Optional) Points to a Java installation.
#   MAVEN_OPTS          (Optional) Java runtime options used when Maven is executed.
#   MAVEN_SKIP_RC       (Optional) Flag to disable loading of mavenrc files.
# -----------------------------------------------------------------------------

# Apache Maven Encrypt Script
#
# Environment Variable Prerequisites
#
#   JAVA_HOME           (Optional) Points to a Java installation.
#   MAVEN_OPTS          (Optional) Java runtime options used when Maven is executed.
#   MAVEN_SKIP_RC       (Optional) Flag to disable loading of mavenrc files.
# -----------------------------------------------------------------------------

  }

  @AndroidIncompatible
  public void testJavaOptional() {
    FreshValueGenerator generator = new FreshValueGenerator();
    assertEquals(Optional.empty(), generator.generateFresh(new TypeToken<Optional<String>>() {}));
    assertEquals(Optional.of("2"), generator.generateFresh(new TypeToken<Optional<String>>() {}));

//
// An object storage system can implement one, multiple, or all functions.
//
//   - Optional (mandatory if <IAMSTS> is true): Set Endpoints for IAM and STS processing.
//
//   - Optional: Set server preferences for Backup & Replication parallel sessions, batch size of deletes, and block sizes (before
//     compression). This is an optional area; by default, there should be no <SystemRecommendations> section in the

        return versionRange.isSelectedVersionKnown(this);
    }

    @Override
    public void setOptional(boolean optional) {
        this.optional = optional;
    }