@SuppressWarnings("unused")
    // Utility method to visualize the full tree for debugging purposes
    public String printTree() {
        StringBuilder sb = new StringBuilder();
        for (PatternToken root : roots) {
            sb.append(printNode(root, 0));
        }
        return sb.toString();
    }
The pattern is split by /, and each token is a node in the tree. Each node either a literal string or "{var}"
representing a variable.

@param pattern of URIs
oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/config/group/uri/quickmatch/PatternTree.java