private BigDecimal factorial(int n) {
        if (n < 0) {
            log.error("Factorial is not defined for negative numbers.");
            return null;
        }
        BigDecimal result = BigDecimal.ONE;
        for (int i = 2; i <= n; i++) {
            result = result.multiply(BigDecimal.valueOf(i));
        }
        return result;
    }
FactorialFunction  ->  factorial(numeric)
Description:
- Return NULL if 'numeric' is NULL;
- Return the factorial of a non-negative
inlong-sdk/transform-sdk/src/main/java/org/apache/inlong/sdk/transform/process/function/arithmetic/FactorialFunction.java