* (prefixed with {@code env.}).
     *
     * @return the system properties, never {@code null}
     */
    @Nonnull
    Map<String, String> getSystemProperties();

    /**
     * Returns the properly overlaid map of properties: system + user.
     */
    @Nonnull
    Map<String, String> getEffectiveProperties();

    /**
     * Returns the start time of the session.
     *

package org.apache.maven.api.cli.cisupport;

import org.apache.maven.api.annotations.Nonnull;

/**
 * CI support: this class contains gathered information and more from CI that Maven process runs on.
 *
 * @since 4.0.0
 */
public interface CIInfo {
    /**
     * Short distinct name of CI system: "GH", "Jenkins", etc.
     */
    @Nonnull
    String name();

    /**

                    Arrays.spliterator(new String[] {"abc", "", "de", "f", "g", ""}),
                    (String str) -> charactersOf(str).spliterator(),
                    Spliterator.SIZED | Spliterator.DISTINCT | Spliterator.NONNULL,
                    7))
        .expect('a', 'b', 'c', 'd', 'e', 'f', 'g');
  }

  public void testFlatMap_nullStream() {
    SpliteratorTester.of(
            () ->
                CollectSpliterators.flatMap(

import org.apache.maven.api.annotations.Nonnull;

/**
 *
 * @since 4.0.0
 */
@Experimental
public interface ArtifactManager extends Service {

    /**
     * Returns the path of the file previously associated to this artifact
     * or {@code Optional.empty()} if no path has been associated.
     */
    @Nonnull
    Optional<Path> getPath(@Nonnull Artifact artifact);

    /**

                    return request;
                }

                @Nonnull
                @Override
                public String getProjectId() {
                    return res.getProjectId();
                }

                @Nonnull
                @Override
                public Optional<Path> getPomFile() {

     *
     * @return the child nodes of this node, never {@code null}
     */
    @Nonnull
    List<Node> getChildren();

    /**
     * @return repositories of this node
     */
    @Nonnull
    List<RemoteRepository> getRemoteRepositories();

    /**
     * The repository where this artifact has been downloaded from.
     */
    @Nonnull
    Optional<RemoteRepository> getRepository();

    /**

     *
     * @return the operating system name (never null)
     */
    @Nonnull
    String name();

    /**
     * Returns the OS architecture as reported by the system property "os.arch".
     * The value is converted to lowercase for consistency.
     *
     * @return the operating system architecture (never null)
     */
    @Nonnull
    String arch();

    /**

     * @param source the source of the project to build
     * @return a new ProjectBuilderRequest
     * @throws NullPointerException if session or source is null
     */
    @Nonnull
    static ProjectBuilderRequest build(@Nonnull Session session, @Nonnull Source source) {
        return builder()
                .session(requireNonNull(session, "session cannot be null"))
                .source(requireNonNull(source, "source cannot be null"))

    /**
     * The packaging id.
     */
    @Nonnull
    @Override
    String id();

    /**
     * The language of this packaging.
     */
    @Nonnull
    default Language language() {
        return type().getLanguage();
    }

    /**
     * The type of main artifact produced by this packaging.
     */
    @Nonnull
    Type type();

    /**

     */
    <T> boolean replace(@Nonnull Key<T> key, @Nullable T oldValue, @Nullable T newValue);

    /**
     * Gets the session data associated with the specified key.
     *
     * @param key the key for which to retrieve the session data, must not be {@code null}
     * @return the session data associated with the key or {@code null} if none
     */
    @Nullable
    <T> T get(@Nonnull Key<T> key);

    /**