@Override
  public Map<String, byte[]> all() {
    List<String> zkSubDirectories = zkClient.getChildren(zkBaseDir);
    Map<String, byte[]> result = new HashMap<>();
    for (String zkSubDir : zkSubDirectories) {
      byte[] value = get(zkSubDir);
      if (value != null) {
        result.put(zkSubDir, value);
      }
    }
    return result;
  }
{@inheritDoc}
@throws SamzaException if there're exceptions reading data from zookeeper.
samza-core/src/main/java/org/apache/samza/zk/ZkMetadataStore.java