var mutex sync.Mutex
	printOnce := make(map[Endpoint]map[string]int)

	return func(endpoint Endpoint, err error, once bool) {
		reqInfo := (&logger.ReqInfo{}).AppendTags("endpoint", endpoint.String())
		ctx := logger.SetReqInfo(GlobalContext, reqInfo)
		mutex.Lock()
		defer mutex.Unlock()

		m, ok := printOnce[endpoint]
		if !ok {
			m = make(map[string]int)
			printOnce[endpoint] = m
			if once {
				m[err.Error()]++

  public Test testsForCheckedMap() {
    return MapTestSuiteBuilder.using(
            new TestStringMapGenerator() {
              @Override
              protected Map<String, String> create(Entry<String, String>[] entries) {
                Map<String, String> map = populate(new HashMap<String, String>(), entries);
                return Collections.checkedMap(map, String.class, String.class);
              }
            })

  public Test testsForCheckedMap() {
    return MapTestSuiteBuilder.using(
            new TestStringMapGenerator() {
              @Override
              protected Map<String, String> create(Entry<String, String>[] entries) {
                Map<String, String> map = populate(new HashMap<String, String>(), entries);
                return Collections.checkedMap(map, String.class, String.class);
              }
            })

    }

    /**
     * Returns a string containing the string representation of each entry of {@code map}, using the
     * previously configured separator and key-value separator.
     */
    public String join(Map<?, ?> map) {
      return join(map.entrySet());
    }

    /**
     * Returns a string containing the string representation of each entry in {@code entries}, using

the back.  However, it was over at last, and they sat down again
in a ring, and begged the Mouse to tell them something more.

  `You promised to tell me your history, you know,' said Alice,
`and why it is you hate--C and D,' she added in a whisper, half
afraid that it would be offended again.

  `Mine is a long and a sad tale!' said the Mouse, turning to
Alice, and sighing.

     * @param callback The function to resolve variable values.
     * @return The interpolated string, or null if the input was null.
     */
    @Nullable
    default String interpolate(@Nullable String val, @Nullable UnaryOperator<String> callback) {
        return interpolate(val, callback, false);
    }

    /**
     * Interpolates a single string value using the provided callback function.
     *

    }

    @Override
    public List<String> convert(final String text, final String field, final String... langs) throws IOException {
        final ReadingConverter converter;
        if (langs == null || langs.length == 0) {
            converter = new LangAnalyzerConverter(null);
        } else {
            final ReadingConverterChain chain = new ReadingConverterChain();
            for (final String lang : langs) {

    String[] array = new String[] {"a"};
    List<String[]> list = ImmutableList.<String[]>of(array);
    assertEquals(singletonList(array), list);
  }

  public void testCopyOf_emptyArray() {
    String[] array = new String[0];
    List<String> list = ImmutableList.copyOf(array);
    assertEquals(emptyList(), list);
  }

  public void testCopyOf_arrayOfOneElement() {
    String[] array = new String[] {"a"};

  private static Test testsForTransform() {
    return CollectionTestSuiteBuilder.using(
            new TestStringCollectionGenerator() {
              @Override
              public Collection<@Nullable String> create(@Nullable String[] elements) {
                List<@Nullable String> list = new ArrayList<>();
                for (String element : elements) {
                  list.add((element == null) ? null : "q" + element);

        fail("Encoding $component $codePoint using $encoding")
      }
      return
    }

    // Check that the URI and HttpURL have the exact same escaping.
    if (toAndFromUri != httpUrl) {
      fail("Encoding $component $codePoint using $encoding")
    }
    if (uri.toString() != httpUrl.toString()) {
      fail("Encoding $component $codePoint using $encoding")
    }
  }