return artifact.isSelectedVersionKnown();
    }

    /** {@inheritDoc} */
    @Override
    public void setOptional(boolean optional) {
        artifact.setOptional(optional);
    }

    /** {@inheritDoc} */
    @Override
    public int hashCode() {
        int result = 17;

        result = 37 * result + getGroupId().hashCode();

    void setRelease(boolean release);

    List<ArtifactVersion> getAvailableVersions();

    void setAvailableVersions(List<ArtifactVersion> versions);

    boolean isOptional();

    void setOptional(boolean optional);

    ArtifactVersion getSelectedVersion() throws OverConstrainedVersionException;

    boolean isSelectedVersionKnown() throws OverConstrainedVersionException;

    }

    @Override
    public boolean isSelectedVersionKnown() throws OverConstrainedVersionException {
        return versionRange.isSelectedVersionKnown(this);
    }

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

                    visit(exclusion);
                }
                // Optional
                org = dependency.getOptional();
                val = interpolate(org);
                if (org != val) {
                    dependency.setOptional(val);
                }
            }
        }

        private void visit(Exclusion exclusion) {
            if (exclusion != null) {

    public boolean isOptional() {
        return (getOptional() != null) ? Boolean.parseBoolean(getOptional()) : false;
    }

            ]]>
          </code>
        </codeSegment>
        <codeSegment>
          <version>4.0.0/4.0.99</version>
          <code>
            <![CDATA[
    public void setOptional(boolean optional) {
        setOptional(String.valueOf(optional));
    }

            Dependency target, Dependency source, boolean sourceDominant, Map<Object, Object> context) {
        String src = source.getOptional();
        if (src != null) {
            if (sourceDominant || target.getOptional() == null) {
                target.setOptional(src);
                target.setLocation("optional", source.getLocation("optional"));
            }
        }
    }

 * is optional or mandatory), and possible exclusions for transitive dependencies.
 * The {@linkplain #getVersionConstraint() version} and the {@linkplain #getOptional() obligation}
 * may not be defined precisely.
 *
 * @since 4.0.0
 */
@Experimental
@Immutable
public interface DependencyCoordinates extends ArtifactCoordinates {
    /**

  private static final Collector<Object, ?, Optional<Object>> TO_OPTIONAL =
      Collector.of(
          ToOptionalState::new,
          ToOptionalState::add,
          ToOptionalState::combine,
          ToOptionalState::getOptional,
          Collector.Characteristics.UNORDERED);

  /**
   * A collector that converts a stream of zero or one elements to an {@code Optional}.
   *

                        dependency = dependency.withScope(managedDependency.getScope());
                    }
                    if (dependency.getOptional() == null && managedDependency.getOptional() != null) {
                        dependency = dependency.withOptional(managedDependency.getOptional());
                    }
                    if (dependency.getExclusions().isEmpty()

            exclusions.add(convert(exclusion));
        }

        return new Dependency(
                artifact,
                dependency.getScope(),
                dependency.getOptional() != null ? dependency.isOptional() : null,
                exclusions);
    }

    private Exclusion convert(org.apache.maven.model.Exclusion exclusion) {