@Override
  public final Object deserialize(Writable blob) throws SerDeException {
    if (!this.charset.equals(Charsets.UTF_8)) {
      blob = transformToUTF8(blob);
    }
    return doDeserialize(blob);
  }
transform Writable data from UTF-8 to charset before serialize.
@param blob
@return
serde/src/java/org/apache/hadoop/hive/serde2/AbstractEncodingAwareSerDe.java