throws GraphConflictResolutionException {
        if (policy == null) {
            throw new GraphConflictResolutionException("no GraphConflictResolutionPolicy injected");
        }

        if (graph == null) {
            return null;
        }

        final MetadataGraphVertex entry = graph.getEntry();
        if (entry == null) {
            return null;
        }

        if (graph.isEmpty()) {

     *
     * @param projectFile The POM file to build the project from, must not be {@code null}.
     * @param request The project building request that holds further parameters, must not be {@code null}.
     * @return The result of the project building, never {@code null}.
     * @throws ProjectBuildingException If the project descriptor could not be successfully built.
     */

  /** Initialized in [callStart]. */
  private var callStackTrace: Any? = null

  /** Finds an exchange to send the next request and receive the next response. */
  private var exchangeFinder: ExchangeFinder? = null

  var connection: RealConnection? = null
    private set
  private var timeoutEarlyExit = false

  /**

        if (artifact == null) {
            return null;
        }

        String version = artifact.getVersion();
        if (version == null && artifact.getVersionRange() != null) {
            version = artifact.getVersionRange().toString();
        }

        Map<String, String> props = null;

      return;
    }

    map.put(null, unmappedValue);
    assertEquals(unmappedValue, map.get(null));
    assertTrue(map.containsKey(null));
    Entry<@Nullable K, V> entry = mapEntry(null, unmappedValue);
    assertTrue(entrySet.remove(entry));
    assertNull(map.get(null));
    assertFalse(map.containsKey(null));
  }

  public void testEntrySetRemoveNullKeyMissing() {

     *
     * @param message The message describing the problem, may be {@code null}.
     * @param severity The severity level of the problem, may be {@code null} to default to
     *            {@link ModelProblem.Severity#ERROR}.
     * @param source The source of the problem, may be {@code null}.
     * @param lineNumber The one-based index of the line containing the error or {@code -1} if unknown.

     */
    @Nonnull
    String getProjectId();

    /**
     * Gets the POM file from which the project was built.
     *
     * @return the optional POM file
     */
    @Nonnull
    Optional<Path> getPomFile();

    /**
     * Gets the project that was built.
     *

                        "name": {
                            "anyOf": [{"type": "string"}, {"type": "null"}],
                            "title": "Name",
                        },
                        "description": {
                            "anyOf": [{"type": "string"}, {"type": "null"}],
                            "title": "Description",
                        },
                        "price": {

        when:
        def p = propertyMetaData.overriddenProperty

        then:
        p == null
    }

    def hasNoOverriddenPropertyWhenGetterAndSetterDoNotOverrideAnything() {
        when:
        def p = propertyMetaData.overriddenProperty

        then:
        p == null
    }

    def "is deprecated when @Deprecated is attached to property"() {

            Element build = root.child("build").orElse(null);
            Element plugins = build.child("plugins").orElse(null);
            Element cleanPlugin = plugins.child("plugin").orElse(null);
            Element executions = cleanPlugin.child("executions").orElse(null);
            Element execution = executions.child("execution").orElse(null);
            Element phase = execution.child("phase").orElse(null);