- circular dependency
- artifact missing
- artifact retrieval exception
- md5 checksum doesn't match for local artifact, need to redownload this
- POM doesn't exist for a goal that requires one
- parent POM missing (in both the repository + relative path)
- component not found

Plugins:
- plugin metadata missing
- plugin metadata retrieval problem
- plugin artifact missing
- plugin artifact retrieval problem

/**
 * Describes a problem that was encountered during model building. A problem can either be an exception that was thrown
 * or a simple string message. In addition, a problem carries a hint about its source, e.g. the POM file that exhibits
 * the problem.
 *
 * @deprecated use {@code org.apache.maven.api.services.ModelBuilder} instead
 */
@Deprecated(since = "4.0.0")
public interface ModelProblem {

    /**

 * specific language governing permissions and limitations
 * under the License.
 */

/**
 * <a href="https://maven.apache.org/resolver/">Maven Resolver</a> extensions for utilizing the Maven POM and Maven
 * repository metadata.
 *
 * @deprecated since 4.0.0, use {@code maven-api-impl} jar instead
 */
@Deprecated(since = "4.0.0")

 */

/**
 * Provides an immutable XML processing API for Maven, offering classes and interfaces
 * for reading, manipulating, and writing XML documents in a thread-safe manner.
 * This package is used extensively for POM, settings, and other Maven configuration files.
 *
 * @since 4.0.0
 */

  <dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>test</groupId>
        <artifactId>a</artifactId>
        <version>0.1</version>
        <scope>import</scope>
        <type>pom</type>
        <classifier>cls</classifier>
      </dependency>
    </dependencies>
  </dependencyManagement>

      </fields>
      <codeSegments>
        <codeSegment>
          <version>4.0.0/4.0.99</version>
          <code>
            <![CDATA[
    /**
     * Gets the POM file for the corresponding project (if any).
     *
     * @return The POM file from which this model originated or {@code null} if this model does not belong to a local
     *         project (e.g. describes the metadata of some artifact from the repository).
     *

 */
@Deprecated
public class UrlModelSource extends UrlSource implements ModelSource {
    /**
     * Creates a new model source backed by the specified URL.
     *
     * @param pomUrl The POM file, must not be {@code null}.
     */
    public UrlModelSource(URL pomUrl) {
        super(pomUrl);
    }

      <snapshotVersion>
        <extension>jar</extension>
        <value>12.2.0-20180814.210714-10</value>
        <updated>20180814210714</updated>
      </snapshotVersion>
      <snapshotVersion>
        <extension>pom</extension>
        <value>12.2.0-20180814.210714-10</value>
        <updated>20180814210714</updated>
      </snapshotVersion>
      <snapshotVersion>
        <classifier>sources</classifier>

 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

/**
 * POM merger.
 */

    /**
     * Returns project's all artifacts as an immutable ordered collection. The collection contains:
     * <ul>
     *   <li>The project's artifacts ({@link Project#getArtifacts()}):
     *     <ul>
     *       <li>The POM artifact (always present)</li>
     *       <li>The main project artifact (if applicable based on packaging)</li>
     *     </ul>
     *   </li>
     *   <li>All attached artifacts in the order they were attached</li>