code: public Conversation conversation(Member author, String content, Map<String, Object> attributes) {
          Conversation conversation = new Conversation(instance);
          conversation.save();
          Expression expression = new Expression(instance);
          DateTime utcNow = new DateTime(DateTime.convertLocalToUtc(new Date()));
          expression.setAuthor(author);
          expression.setAuthoredAt(utcNow);
          expression.setContent(content);
          expression.setBelongsTo(conversation);
          addAttributes(expression, attributes);
          expression.save();
          return conversation;
      }
docs: Adds new Conversation.
  @param author Author of Expression in Conversation.
  @param content Content of Expression in Conversation.
  @param attributes Additional attributes that should be set for Conversation Expression.
  @return Newly created Conversation