code: public Map<String, Long> releaseLocks(boolean force) throws Exception {
          Map<String, Long> locksToDelete = readLockColumns();
  
          MutationBatch m = keyspace.prepareMutationBatch().setConsistencyLevel(consistencyLevel);
          ColumnListMutation<String> row = m.withRow(columnFamily, key);
          long now = getCurrentTimeMicros();
          for (Entry<String, Long> c : locksToDelete.entrySet()) {
              if (force || (c.getValue() > 0 && c.getValue() < now)) {
                  row.deleteColumn(c.getKey());
              }
          }
          m.execute();
  
          return locksToDelete;
      }
docs: Delete locks columns. Set force=true to remove locks that haven't
  expired yet.
  
  This operation first issues a read to cassandra and then deletes columns
  in the response.
  
  @param force - Force delete of non expired locks as well
  @return Map of locks released
  @throws Exception