// Verify success
            assertEquals(0, result, "Apply should succeed");

            // Verify POM was upgraded
            String upgradedPom = Files.readString(pomFile);
            assertTrue(
                    upgradedPom.contains("http://maven.apache.org/POM/4.1.0"),
                    "POM should be upgraded to 4.1.0 namespace");
        }

        @Test

public interface ModelResolver {

    /**
     * Tries to resolve the POM for the specified coordinates.
     *
     * @param groupId The group identifier of the POM, must not be {@code null}.
     * @param artifactId The artifact identifier of the POM, must not be {@code null}.
     * @param version The version of the POM, must not be {@code null}.
     * @return The source of the requested POM, never {@code null}.

         * Base validation level that applies to all POM versions.
         * Includes fundamental structural validations.
         */
        BASE,

        /**
         * Validation for Maven 2.0 POM format.
         */
        V20,

        /**
         * Validation for Maven 3.0 POM format.
         */
        V30,

        /**
         * Validation for Maven 3.1 POM format.
         */
        V31,

    /**
     * Get the location of the POM from which this POM was imported from.
     * Can return {@code null} if this POM was not imported.
     *
     * @return the InputLocation where this POM was imported from, or null if not imported
     */
    public InputLocation getImportedFrom() {
        return importedFrom;
    }

    /**
     * Set the location of the POM from which this POM was imported from.
     *

    private static final String BASE1_ID = "thegroup:base1:pom";
    private static final String BASE1_ID2 = "thegroup:base1:1";

    private static final String BASE1 = "<project>\n" + "  <modelVersion>4.0.0</modelVersion>\n"
            + "  <groupId>thegroup</groupId>\n"
            + "  <artifactId>base1</artifactId>\n"
            + "  <version>1</version>\n"
            + "  <packaging>pom</packaging>\n"
            + "  <dependencyManagement>\n"

import static eu.maveniverse.domtrip.maven.MavenPomElements.Elements.MODULES;
import static eu.maveniverse.domtrip.maven.MavenPomElements.Files.POM_XML;

/**
 * Discovers and loads Maven POM files in a Maven project hierarchy.
 *
 * <p>This class recursively discovers all POM files in a Maven project hierarchy
 * and loads them as domtrip Documents. Individual strategies can create domtrip Editors

        file("build/distributions/hello-world-1.0-sources.jar").exists()
        file("build/distributions/hello-world-1.0.pom").exists()
        assertXmlEquals(file("build/distributions/hello-world-1.0.pom").text, """
            <project xmlns="http://maven.apache.org/POM/4.0.0" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

            Map<Path, Document> pomMap = new HashMap<>();
            pomMap.put(Paths.get("project", "pom.xml"), parentDoc);
            pomMap.put(Paths.get("project", "module-a", "pom.xml"), moduleADoc);
            pomMap.put(Paths.get("project", "module-b", "pom.xml"), moduleBDoc);

            Editor editor = new Editor(moduleBDoc);
            Element moduleBRoot = editor.root();

 * </ul>
 * <p>
 * <b>Mixin Handling</b>: Mixins are only supported in model version 4.2.0 or later. If a POM contains mixins:
 * <ul>
 *   <li>Setting {@code preserve.model.version=true} preserves them in the consumer POM with model version 4.2.0</li>
 *   <li>Setting {@code maven.consumer.pom.flatten=true} removes them during transformation</li>

KIND, either express or implied.  See the License for the
specific language governing permissions and limitations
under the License.
-->

<paramdoc xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 ../../../../../../../maven-plugin-parameter-documenter/target/generated-site/xsd/paramdoc-1.0.0.xsd ">
<expressions>
  <expression>