public GroupingOperation addChildren(List<GroupingOperation> lst) {
        for (GroupingOperation op : lst) {
            addChild(op);
        }
        return this;
    }
Convenience method to call {@link #addChild(GroupingOperation)} for each element in the given list.

@param lst the list of operations to add
@return this, to allow chaining
container-search/src/main/java/com/yahoo/search/grouping/request/GroupingOperation.java