public TraceNode normalize() {
        compact();
        sort();
        if (note != null || !strict) {
            TraceNode child = new TraceNode();
            child.swap(this);
            addChild(child);
            strict = true;
        }
        return this;
    }
Normalize this tree. This will transform all equivalent trees into the same form. Note that this will also
perform an implicit compaction of the tree.

@return This, to allow chaining.
messagebus/src/main/java/com/yahoo/messagebus/TraceNode.java