@Override
    public Object parse(SourceData sourceData, int rowIndex, Context context) {
        if (separator == null) {
            return null;
        }
        StringBuilder result = new StringBuilder();
        boolean firstStrFlag = true;
        for (ValueParser node : nodeList) {
            if (node != null) {
                Object parsedValue = node.parse(sourceData, rowIndex, context);
                if (parsedValue != null) {
                    if (!firstStrFlag) {
                        result.append(separator);
                    }
                    result.append(parsedValue);
                    firstStrFlag = false;
                }
            }
        }
        return result.toString();
    }
ConcatWsFunction  ->  concat_ws(string1, string2, string3,...)
description:
- Return NULL If STRING1 is NULL.
- Return a string that concatenates (STRING2, STRING3, ...) with a separator STRING1.
inlong-sdk/transform-sdk/src/main/java/org/apache/inlong/sdk/transform/process/function/string/ConcatWsFunction.java