code: public ArrayList<DatanodeDescriptor> getDecommissioningNodesList() {
  
      try {
        return getDecommissioningNodesList(getDatanodeListForReport(DatanodeReportType.LIVE));
      } catch (Exception e) {
        return new ArrayList<DatanodeDescriptor>();
      }
    }
docs: /*
  @return list of datanodes where decommissioning is in progress