@Override
    public Object parse(SourceData sourceData, int rowIndex, Context context) {
        Map<Object, Object> res = new HashMap<>();
        for (ValueParser valueParser : parserList) {
            Object mapObj = valueParser.parse(sourceData, rowIndex, context);
            if (mapObj == null) {
                return null;
            }
            if (mapObj instanceof Map) {
                Map<?, ?> map = (Map<?, ?>) mapObj;
                if (map.isEmpty()) {
                    return null;
                }
                res.putAll(map);
            }
        }
        return res;
    }
MapUnionFunction  ->  MAP_UNION([map1, map2, ...])
description:
- Return NULL if any of maps is null
- Return a map created by merging at least one map.These maps should have a common map type,the following map will overwrite the previous one.
inlong-sdk/transform-sdk/src/main/java/org/apache/inlong/sdk/transform/process/function/collection/MapUnionFunction.java