hmset命令报错 value sent to redis cannot be null

redis存入hash结构时, key, hkey, hvalue 均不能为null

public void hmset(final String key, final Map<String, String> hash) {
    final Map<byte[], byte[]> bhash = new HashMap<byte[], byte[]>(hash.size());
    for (final Entry<String, String> entry : hash.entrySet()) {
      bhash.put(SafeEncoder.encode(entry.getKey()), SafeEncoder.encode(entry.getValue()));
    }
    hmset(SafeEncoder.encode(key), bhash);
  }

public static byte[] encode(final String str) {
    try {
      if (str == null) {
        throw new JedisDataException("value sent to redis cannot be null");
      }
      return str.getBytes(Protocol.CHARSET);
    } catch (UnsupportedEncodingException e) {
      throw new JedisException(e);
    }
  }