public static <T> List<T> union(List<T> list1, List<T> list2) {
        final ArrayList<T> result = new ArrayList<>(list1);
        result.addAll(list2);
        return result;
    }
Returns a union list of two lists
@param list1
@param list2
@return A union list of two lists
@param <T> Elements type
inlong-common/src/main/java/org/apache/inlong/common/util/ListUtil.java