code: private static Map<byte[], byte[]> createCfRenameMap(Configuration conf) {
      Map<byte[], byte[]> cfRenameMap = null;
      String allMappingsPropVal = conf.get(CF_RENAME_PROP);
      if(allMappingsPropVal != null) {
        // The conf value format should be sourceCf1:destCf1,sourceCf2:destCf2,...
        String[] allMappings = allMappingsPropVal.split(",");
        for (String mapping: allMappings) {
          if(cfRenameMap == null) {
              cfRenameMap = new TreeMap<byte[],byte[]>(Bytes.BYTES_COMPARATOR);
          }
          String [] srcAndDest = mapping.split(":");
          if(srcAndDest.length != 2) {
              continue;
          }
          cfRenameMap.put(srcAndDest[0].getBytes(), srcAndDest[1].getBytes());
        }
      }
      return cfRenameMap;
    }
docs: helper: make a map from sourceCfName to destCfName by parsing a config key