/**
 * 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.
 *
 */
public interface ModelProblem extends BuilderProblem {

    /**
     * Enumeration of model versions that can be validated.

 * under the License.
 */
package org.apache.maven.api.model;

import java.io.Serializable;
import java.util.Collection;
import java.util.List;
import java.util.Objects;
import java.util.stream.Collectors;
import java.util.stream.Stream;

/**
 * Represents the source of a model input, such as a POM file.
 * <p>
 * This class tracks the origin of model elements, including their location in source files

        </field>
      </fields>
      <codeSegments>
        <codeSegment>
          <version>2.0.0+</version>
          <code><![CDATA[
    /**
     * Get the effective ID of this phase, e.g.,
     * {@code generate-sources} or {@code after:integration-test[1000]}.
     *
     * @return String
     */
    public String getEffectiveId() {
        if (executionPoint == null) {

 */

/**
 * Maven Immutable POM (Project Object Model) classes, generated from <code>maven.mdo</code> model.
 * <p>
 * This package contains the data model classes that represent the structure of Maven POM files.
 * These classes are immutable to ensure thread safety and prevent unintended modifications.
 * The root class is {@link org.apache.maven.api.model.Model}, which represents the entire POM.
 * <p>
 * Key components include:

import org.apache.maven.api.annotations.Nonnull;
import org.apache.maven.api.model.Model;

/**
 * Provides the super POM that all models implicitly inherit from.
 *
 * @since 4.0.0
 */
@Experimental
public interface SuperPomProvider extends Service {

    /**
     * Gets the super POM for the specified model version.
     *
     * @param version The model version to retrieve the super POM for (e.g. "4.0.0"), must not be {@code null}.

     *   <li>
     *     If no module name, then the default directory is
     *     <code>src/{@linkplain #scope() scope}/{@linkplain #language() language}</code>.
     *   </li><li>
     *     If a module name is present, then the default directory is
     *     <code>src/{@linkplain #module() module}/{@linkplain #scope() scope}/{@linkplain #language() language}</code>.
     *   </li>
     * </ul>
     *
     * The default value is relative.

     * Can return {@code null}.
     *
     * @return InputLocation
     * @since 4.0.0
     */
    @Override
    public InputLocation getImportedFrom() {
        return importedFrom;
    }

    /**
     * Merges the {@code source} location into the {@code target} location.
     *
     * @param target the target location

    @Override
    public Model interpolate(Model model, Map<String, ?> context, boolean strict) throws ModelInterpolationException {
        Properties props = new Properties();
        props.putAll(context);

        return interpolate(model, null, new DefaultProjectBuilderConfiguration().setExecutionProperties(props), true);
    }

    @Override

### Input Model in Docs { #input-model-in-docs }

You can confirm that in the docs, the `description` field doesn't have a **red asterisk**, it's not marked as required:

<div class="screenshot">
<img src="/img/tutorial/separate-openapi-schemas/image01.png">
</div>

### Model for Output { #model-for-output }

But if you use the same model as an output, like here:

# Extra Models { #extra-models }

Continuing with the previous example, it will be common to have more than one related model.

This is especially the case for user models, because:

* The **input model** needs to be able to have a password.
* The **output model** should not have a password.
* The **database model** would probably need to have a hashed password.

/// danger