code: public static String keyVersionToString(ByteArray key,
              Map<Value, Set<ClusterNode>> versionMap,
              String storeName,
              Integer partitionId) {
          StringBuilder record = new StringBuilder();
          for (Map.Entry<Value, Set<ClusterNode>> versionSet : versionMap.entrySet()) {
              Value value = versionSet.getKey();
              Set<ClusterNode> nodeSet = versionSet.getValue();
  
              record.append("BAD_KEY,");
              record.append(storeName + ",");
              record.append(partitionId + ",");
              record.append(ByteUtils.toHexString(key.get()) + ",");
              record.append(nodeSet.toString().replace(", ", ";") + ",");
              record.append(value.toString());
          }
          return record.toString();
      }
docs: Convert a key-version-nodeSet information to string
  
  @param key The key
  @param versionMap mapping versions to set of PrefixNodes
  @param storeName store's name
  @param partitionId partition scanned
  @return a string that describe the information passed in