distributed/src/main/java/com/orientechnologies/orient/server/distributed/impl/ODatabaseDocumentDistributed.java
public Map<String, Set<String>> getActiveDataCenterMap() {
    Map<String, Set<String>> result = new HashMap<>();
    ODistributedConfiguration cfg = getDistributedConfiguration();
    Set<String> servers = cfg.getRegisteredServers();
    for (String server : servers) {
      String dc = cfg.getDataCenterOfServer(server);
      Set<String> dcConfig = result.get(dc);
      if (dcConfig == null) {
        dcConfig = new HashSet<>();
        result.put(dc, dcConfig);
      }
      dcConfig.add(server);
    }
    return result;
  }
public Map<String, Set<String>> getActiveDataCenterMap() {
    Map<String, Set<String>> result = new HashMap<>();
    ODistributedConfiguration cfg = getDistributedConfiguration();
    Set<String> servers = cfg.getRegisteredServers();
    for (String server : servers) {
      String dc = cfg.getDataCenterOfServer(server);
      Set<String> dcConfig = result.get(dc);
      if (dcConfig == null) {
        dcConfig = new HashSet<>();
        result.put(dc, dcConfig);
      }
      dcConfig.add(server);
    }
    return result;
  }
returns the data center map for current deploy. The keys are data center names, the values are node names per data center

@return data center map for current deploy