code: private Map<String, String> generateSidToHost() {
          Map<String, String> sidToHostname = new HashMap<>();
          if (oldAssignment != null) {
              sidToHostname.putAll(oldAssignment.getNodeHost());
          }
  
          for (Entry<String, SupervisorInfo> entry : cluster.entrySet()) {
              String supervisorId = entry.getKey();
              SupervisorInfo supervisorInfo = entry.getValue();
  
              sidToHostname.put(supervisorId, supervisorInfo.getHostName());
  
          }
  
          return sidToHostname;
      }
docs: Do we need just handle the case when type is ASSIGN_TYPE_NEW?