private PathPatternNode<V, VSerializer> getRoot(String rootName) {
    return rootMap.computeIfAbsent(rootName, r -> new PathPatternNode<>(r, supplier, serializer));
  }
Create PatternTreeMap.

@param supplier provide type of set to store values on PathPatternNode
@param appendFunction define the merge logic of append value
@param deleteFunction define the split logic of delete value
iotdb-core/node-commons/src/main/java/org/apache/iotdb/commons/path/PatternTreeMap.java