public static void logIfUnexpected(Logger logger, Channel ch, Throwable cause) {
        requireNonNull(logger, "logger");
        requireNonNull(ch, "ch");
        requireNonNull(cause, "cause");
        if (!logger.isWarnEnabled() || isExpected(cause)) {
            return;
        }

        logger.warn("{} Unexpected exception:", ch, cause);
    }
Logs the specified exception if it is {@linkplain #isExpected(Throwable) unexpected}.
core/src/main/java/com/linecorp/armeria/common/util/Exceptions.java