if (synonymLoader.getSynonymMap() == null) {
            if (settings.getAsList("synonyms", null) != null) {
                logger.warn("synonyms values are empty.");
            } else if (settings.get("synonyms_path") != null) {
                logger.warn("synonyms_path[{}] is empty.", settings.get("synonyms_path"));
            } else {

        this.servers = (servers != null) ? servers : new ArrayList<>();
        this.proxies = (proxies != null) ? proxies : new ArrayList<>();
        this.problems = (problems != null) ? problems : new ArrayList<>();
    }

    @Override
    public Server getServer() {
        return servers.isEmpty() ? null : servers.get(0);
    }

    @Override
    public List<Server> getServers() {

        if (spec == null) {
            return null;
        }

        VersionRange cached = CACHE_SPEC.get(spec);
        if (cached != null) {
            return cached;
        }

        List<Restriction> restrictions = new ArrayList<>();
        String process = spec;
        ArtifactVersion version = null;
        ArtifactVersion upperBound = null;
        ArtifactVersion lowerBound = null;

     *   <li>Ensures no null repository entries exist in the list</li>
     * </ul>
     *
     * <p>Duplicate detection is based on the {@code RemoteRepository#equals(Object)}
     * method, which typically compares repository IDs and URLs.
     *
     * @param repositories the list of repositories to validate, may be {@code null}
     * @return the same list if validation passes, or {@code null} if input was {@code null}

     * @param resource the resource to track
     * @return resource ID for tracking
     */
    public String registerResource(AutoCloseable resource) {
        if (resource == null) {
            throw new IllegalArgumentException("Resource cannot be null");
        }

        String resourceId = generateResourceId(resource);
        ResourceHolder holder = new ResourceHolder(resourceId, resource, referenceQueue);

    Preconditions.checkNotNull(task, "task must not be null!");
    Preconditions.checkNotNull(result, "result must not be null!");
    return delegate.submit(task, result);
  }

  @Override
  public ListenableFuture<?> submit(Runnable task) {
    Preconditions.checkNotNull(task, "task must not be null!");
    return delegate.submit(task);
  }

  @Override
  public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks)

    Preconditions.checkNotNull(task, "task must not be null!");
    Preconditions.checkNotNull(result, "result must not be null!");
    return delegate.submit(task, result);
  }

  @Override
  public ListenableFuture<?> submit(Runnable task) {
    Preconditions.checkNotNull(task, "task must not be null!");
    return delegate.submit(task);
  }

  @Override
  public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks)

        msg += (version != null ? version : "<version unknown>");
        if (rev != null || timestamp != null) {
            msg += " (";
            msg += (rev != null ? rev : "");
            if (timestamp != null && !timestamp.isEmpty()) {
                String ts = formatTimestamp(Long.parseLong(timestamp));
                msg += (rev != null ? "; " : "") + ts;
            }
            msg += ")";

        SpnegoException ex = new SpnegoException();

        // Then
        assertNotNull(ex, "Exception should be created");
        assertNull(ex.getMessage(), "Default message should be null");
        assertNull(ex.getCause(), "Default cause should be null");
        assertTrue(ex instanceof CIFSException, "Should be a CIFSException");
        assertTrue(ex instanceof IOException, "Should be an IOException");
    }

    @Test

        if (createdBy != null) {
            addFieldToSource(sourceMap, "createdBy", createdBy);
        }
        if (createdTime != null) {
            addFieldToSource(sourceMap, "createdTime", createdTime);
        }
        if (generator != null) {
            addFieldToSource(sourceMap, "generator", generator);
        }
        if (path != null) {
            addFieldToSource(sourceMap, "path", path);