public MutableMessageSerializer {
  private ObjectMapper mapper = new ObjectMaper();

  public static class MutableMessage {
    private String content;
    private String sender;

    public void setContent(String content) {
      this.content = content;
    }

    public String getContent() {
      return this.content;
    }

    @JsonIgnore
    public void setSender(String sender) {
      this.sender = sender;
    }

    @JsonIgnore
    public String getSender() {
      return this.sender;
    }
  }

  public MutableMessage deserialize(byte[] content) throws Exception {
    return mapper.readValue(content, MutableMessage.class);
  }

  public byte[] serialize(MutableMessage message) throws Exception {
    return mapper.writeValueAsBytes(message);
  }
}