public static void build() {
      if (CONSENSU_GROUP_ID_2_INSTANCE_MAP == null) {
        CONSENSU_GROUP_ID_2_INSTANCE_MAP = new ConcurrentHashMap<>();
      }
    }
This is a hook function, which will be automatically invoked when deletionResource's reference
count returns to 0.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/pipe/consensus/deletion/DeletionResourceManager.java