@Override
    public Object parse(SourceData sourceData, int rowIndex, Context context) {
        Object stringObj = stringParser.parse(sourceData, rowIndex, context);
        if (stringObj == null) {
            return null;
        }
        return stringObj.toString().toUpperCase();
    }
UpperFunction  -> UPPER(s)
description:
- Return NULL if 's' is NULL;
- Return the result of converting 's' to uppercase
inlong-sdk/transform-sdk/src/main/java/org/apache/inlong/sdk/transform/process/function/string/UpperFunction.java