Throwable error = null;

                if (project == null) {
                    project = new MavenProject();
                    project.setFile(pomFile != null ? pomFile.toFile() : null);

                    boolean reactorMember = pomFile != null
                            && session.getProjects() != null // this is for UTs

            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);

  * When annotating existing internal code, use `org.jetbrains.annotations.Contract`, e.g. `@Contract(null -> null; !null -> !null)`.
      When doing so, still annotate nullable parameters and the return type as `@Nullable`.
  * Do not use `@Contract` for public APIs.
  * For polynull public APIs, the solution has to be decided on a case-by-case basis.

Do not remove `null` checks on public API boundaries, even if the annotations (or rather lack of them) suggest this.

                        lineNumber, columnNumber, source != null ? source.toApiSource() : null);
            }
        } else {
            return org.apache.maven.api.model.InputLocation.of(
                    lineNumber,
                    columnNumber,
                    source != null ? source.toApiSource() : null,
                    locations != null

        this.syncContextFactory = Objects.requireNonNull(syncContextFactory, "syncContextFactory cannot be null");
        this.repositoryEventDispatcher =
                Objects.requireNonNull(repositoryEventDispatcher, "repositoryEventDispatcher cannot be null");
        this.versionScheme = Objects.requireNonNull(versionScheme, "versionScheme cannot be null");
    }

    @Override

        // Check build/plugins
        Element buildElement = root.child(BUILD).orElse(null);
        if (buildElement != null) {
            Element pluginsElement = buildElement.child(PLUGINS).orElse(null);
            if (pluginsElement != null) {
                hasUpgrades |= upgradePluginsInSection(

        ClassRealm pluginRealm = pluginDescriptor.getClassRealm();

        if (pluginRealm == null) {
            try {
                setupPluginRealm(pluginDescriptor, session, null, null, null);
            } catch (PluginResolutionException e) {
                String msg = "Cannot setup plugin realm [mojoDescriptor=" + mojoDescriptor.getId()

     *
     * @param project The project to try to resolve the artifact from, must not be <code>null</code>.
     * @param requestedArtifact The artifact to resolve, must not be <code>null</code>.
     * @return The matching artifact from the project or <code>null</code> if not found. Note that this
     */
    private Artifact findMatchingArtifact(MavenProject project, Artifact requestedArtifact) {

        return build(session, artifactCoordinates, null, null);
    }

    /**
     * Creates a version range resolver request.
     *
     * @param session the session to use, must not be {@code null}
     * @param artifactCoordinates the artifact coordinates whose version range should be resolved, must not be {@code null}
     * @param repositories the repositories to use, or {@code null} to use the session's repositories

                coreExtension.setGroupId(interpolatedTrimmed(parser.nextText(), "groupId"));
            } else if (checkFieldWithDuplicate(parser, "artifactId", null, parsed)) {
                coreExtension.setArtifactId(interpolatedTrimmed(parser.nextText(), "artifactId"));
            } else if (checkFieldWithDuplicate(parser, "version", null, parsed)) {