public static UnprocessedRequestException of(Throwable cause) {
        requireNonNull(cause, "cause");
        if (cause instanceof UnprocessedRequestException) {
            return (UnprocessedRequestException) cause;
        }
        return new UnprocessedRequestException(cause);
    }
Returns a new {@link UnprocessedRequestException} with the specified {@code message} and
{@link Throwable}.
core/src/main/java/com/linecorp/armeria/client/UnprocessedRequestException.java