@Override
    public Object parse(SourceData sourceData, int rowIndex, Context context) {
        BigDecimal maxValue = null;
        for (ValueParser valueParser : parserList) {
            Object valueObj = valueParser.parse(sourceData, rowIndex, context);
            if (valueObj == null) {
                return null;
            }

            BigDecimal value = OperatorTools.parseBigDecimal(valueObj);
            if (maxValue == null || value.compareTo(maxValue) > 0) {
                maxValue = value;
            }
        }
        return maxValue;
    }
GreatestFunction  ->  GREATEST(value1[, value2, ...])
description:
- Return NULL if any parameter is null
- Return the greatest value of the list of arguments.
inlong-sdk/transform-sdk/src/main/java/org/apache/inlong/sdk/transform/process/function/arithmetic/GreatestFunction.java