@Override
  public DataNodeId getDataNodeId(String hostname, int port) {
    DataNodeId dataNode = staticClusterManager.getDataNodeId(hostname, port);
    if (dataNode == null) {
      dataNode = helixClusterManager.getDataNodeId(hostname, port);
    }
    return dataNode;
  }
Return the {@link DataNodeId} associated with the given hostname and port in the underlying
{@link StaticClusterManager}. If not found in static cluster map, then get the same from helix cluster map.
@param hostname of the DataNodeId
@param port of the DataNodeId
@return the {@link DataNodeId} associated with the given hostname and port.
ambry-clustermap/src/main/java/com/github/ambry/clustermap/RecoveryTestClusterManager.java