import org.codehaus.plexus.util.xml.XmlStreamReader;
import org.codehaus.plexus.util.xml.pull.EntityReplacementMap;
import org.codehaus.plexus.util.xml.pull.MXParser;
import org.codehaus.plexus.util.xml.pull.XmlPullParser;
import org.codehaus.plexus.util.xml.pull.XmlPullParserException;

/**
 * Class CoreExtensionsXpp3Reader.
 *

                "Constructor com.example.Source(java.util.List): Parameter 0 from null accepting to non-null accepting breaking change."
            )
            assertHasNoWarning()
            assertHasNoInformation()
        }
    }

    @Test
    fun `from null array returning to non-null returning is not breaking`() {

     *            information along, may be <code>null</code>.
     */
    public void merge(Model target, Model source, boolean sourceDominant, Map<?, ?> hints) {
        Objects.requireNonNull(target, "target cannot be null");

        if (source == null) {
            return;
        }

        Map<Object, Object> context = new HashMap<>();
        if (hints != null) {
            context.putAll(hints);
        }

                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

                qualifier = version;
                majorVersion = null;
                minorVersion = null;
                incrementalVersion = null;
                buildNumber = null;
            }
        }
    }

    private static boolean isDigits(String cs) {
        if (cs == null || cs.isEmpty()) {
            return false;
        }
        final int sz = cs.length();

     *
     * @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) {

            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);

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

        VersionRange cached = CACHE_SPEC.get(spec);
        if (cached != null) {
            return cached;
        }

        List<Restriction> restrictions = new ArrayList<>();
        String process = spec;
        ArtifactVersion version = null;
        ArtifactVersion upperBound = null;
        ArtifactVersion lowerBound = null;

        if (settings.isUsePluginRegistry()) {
            addViolation(problems, Severity.WARNING, "usePluginRegistry", null, "is deprecated and has no effect.");
        }

        List<String> pluginGroups = settings.getPluginGroups();

        if (pluginGroups != null) {
            for (int i = 0; i < pluginGroups.size(); i++) {
                String pluginGroup = pluginGroups.get(i).trim();

  * 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.