public static HttpStatusClass valueOf(int code) {
        if (INFORMATIONAL.contains(code)) {
            return INFORMATIONAL;
        }
        if (SUCCESS.contains(code)) {
            return SUCCESS;
        }
        if (REDIRECTION.contains(code)) {
            return REDIRECTION;
        }
        if (CLIENT_ERROR.contains(code)) {
            return CLIENT_ERROR;
        }
        if (SERVER_ERROR.contains(code)) {
            return SERVER_ERROR;
        }
        return UNKNOWN;
    }
Returns the class of the specified HTTP status code.
core/src/main/java/com/linecorp/armeria/common/HttpStatusClass.java