public void dump() {
    System.out.println("map " + map.size());
    System.out.println("isAllModified " + isAllModified());
    System.out.println("isEmpty " + isEmpty());
    for (Map.Entry<Long, BitSetNode> entry : map.entrySet()) {
      entry.getValue().dump();
    }
  }
Merges {@code leftNode} & {@code rightNode} and updates the map.
hbase-procedure/src/main/java/org/apache/hadoop/hbase/procedure2/store/wal/ProcedureStoreTracker.java