private static boolean needsNormalization(String hostname) {
        final int length = hostname.length();
        for (int i = 0; i < length; i++) {
            final int c = hostname.charAt(i);
            if (c > 0x7F) {
                return true;
            }
        }
        return false;
    }
IDNA ASCII conversion and case normalization.
core/src/main/java/com/linecorp/armeria/internal/common/TlsProviderUtil.java