.values()
                .stream()
                .map(MavenProject::getVersion)
                .collect(Collectors.collectingAndThen(Collectors.toList(), Collections::unmodifiableList));
        if (!versions.isEmpty()) {
            return versions;
        }
        return getAllProjects()
                .getOrDefault(artifact.getGroupId(), Collections.emptyMap())

        }
    }

    @Nonnull
    @Override
    public List<RemoteRepository> getRemoteRepositories() {
        return Collections.unmodifiableList(repositories);
    }

    @Nonnull
    @Override
    public SessionData getData() {
        org.eclipse.aether.SessionData data = session.getData();
        return new SessionData() {

      } else if (collection instanceof Set) {
        return Collections.unmodifiableSet((Set<E>) collection);
      } else if (collection instanceof List) {
        return Collections.unmodifiableList((List<E>) collection);
      } else {
        return Collections.unmodifiableCollection(collection);
      }
    }

    @Override

/**
 */
@Named
@Singleton
public class DefaultModelValidator implements ModelValidator {

    public static final List<String> VALID_MODEL_VERSIONS =
            Collections.unmodifiableList(Arrays.asList("4.0.0", "4.1.0"));

    private static final Pattern EXPRESSION_NAME_PATTERN = Pattern.compile("\\$\\{(.+?)}");

          array[count] = iterator.next();
        }
        for (int i = count; i < size; i++) {
          array[i] = null; // for GWT
        }

        List<@Nullable T> list = Collections.unmodifiableList(Arrays.asList(array));
        // TODO(b/192579700): Use a ternary once it no longer confuses our nullness checker.
        if (pad || count == size) {
          return list;
        } else {