private void deserialize() {
        if (decoder != null && buffer != null) {
            decoder.decode(this, buffer);
            decoder = null;
            buffer = null;
        }
    }
This method will make sure that any serialized content is deserialized into proper message content on first
entry. Any subsequent entry into this function will do nothing.
documentapi/src/main/java/com/yahoo/documentapi/messagebus/protocol/GetDocumentReply.java