public static ProfileStackNode newNode() {
        ProfileStackNode emptyNode = new ProfileStackNode();
        emptyNode.detectedStacks = new LinkedList<>();
        emptyNode.children = new ArrayList<>();
        return emptyNode;
    }
create new empty, un-init node
oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/profiling/trace/analyze/ProfileStackNode.java