import org.apache.maven.api.annotations.Nullable;

import static org.apache.maven.api.services.BaseRequest.nonNull;

/**
 * A Source specific to load POMs.  The {@link #resolve(ModelLocator, String)} method
 * will be used to find POMs for children modules.
 *
 * @since 4.0.0
 */
public interface ModelSource extends Source {

    interface ModelLocator {
        /**
         * Returns the file containing the pom or null if a pom can not be

        File txtFile = new File("target/test-classes/source.txt");
        FileSource source = new FileSource(txtFile);
        assertEquals(txtFile.getAbsolutePath(), source.getLocation());
    }

    @Test
    void testGetFile() {
        File txtFile = new File("target/test-classes/source.txt");
        FileSource source = new FileSource(txtFile);
        assertEquals(txtFile.getAbsoluteFile(), source.getFile());
    }

        return builder(nonNull(request, "request cannot be null"))
                .source(nonNull(source, "source cannot be null"))
                .build();
    }

    @Nonnull
    static ModelBuilderRequest build(@Nonnull Session session, @Nonnull ModelSource source) {
        return builder()

        }
    }

    private static final class SourceCacheKey {
        private final Source source;

        private final String tag;

        private final int hash;

        SourceCacheKey(Source source, String tag) {
            this.source = source;
            this.tag = tag;
            this.hash = Objects.hash(source, tag);
        }

        @Override
        public String toString() {

    }

    @Override
    public String toString() {
        return "[ " + "FROM:("
                + (source == null ? "no source" : (source.md == null ? "no source MD" : source.md.toString())) + ") "
                + "TO:(" + (target == null ? "no target" : (target.md == null ? "no target MD" : target.md.toString()))
                + ") " + "version=" + version + ", scope=" + (scope == null ? "null" : scope.getScope()) + ", depth="

  + Only use spaces for indentation.
  + Create minimal diffs - disable on save actions like reformat source code or organize imports.
    If you feel the source code should be reformatted, create a separate PR for this change.
  + Check for unnecessary whitespace with `git diff --check` before committing.
+ Make sure your commit messages are in the proper format. Your commit message should contain the key of the JIRA issue.
```

    @Inject
    private ArtifactFactory artifactFactory;

    private ArtifactSpec projectArtifact;

    private Source source;

    private static final String GROUP_ID = "test";

    @BeforeEach
    void setUp() throws Exception {
        source = new Source();

        projectArtifact = createArtifactSpec("project", "1.0", null);
    }

    @Test

  <groupId>org.apache.maven.its.it0052</groupId>
  <artifactId>maven-it-it0052</artifactId>
  <version>1.0</version>
  <packaging>jar</packaging>

  <name>Maven Integration Test :: it0052</name>
  <description>Test that source attachment doesn't take place when -DperformRelease=true is missing.</description>

  <!-- NOTE: Use stub versions of the core plugins referenced by the build -->
  <build>
    <pluginManagement>
      <plugins>

        }
    }

    private static <T> T cache(ModelCache cache, Source source, String tag, Callable<T> supplier) {
        Supplier<T> s = asSupplier(supplier);
        if (cache == null) {
            return s.get();
        } else {
            return cache.computeIfAbsent(source, tag, s);
        }
    }

    private static <T> Supplier<T> asSupplier(Callable<T> supplier) {

            throw new IllegalArgumentException("reader or inputStream must be non null");
        }
        try {
            InputSource source = null;
            if (request.getModelId() != null || request.getLocation() != null) {
                source = new InputSource(request.getModelId(), request.getLocation());
            }
            MavenToolchainsStaxReader xml = new MavenToolchainsStaxReader();