src/main/java/board/Board.java
public void addTopic(Topic topic) throws BoardException {
    if (topics.containsKey(topic)) {
      throw new TopicExistsException();
    }
    topics.put(topic, new LinkedHashSet<>());
  }
/**
   * addTopic to the Board.
   *
   * @throws BoardException If the Topic is already on the Board.
   */
addTopic to the Board.
@throws BoardException If the Topic is already on the Board.
addTopic to the Board . @throws BoardException If the Topic is already on the Board .
public void addTopic(Topic topic) throws BoardException {
    if (topics.containsKey(topic)) {
      throw new TopicExistsException();
    }
    topics.put(topic, new LinkedHashSet<>());
  }
public void addTopic ( Topic topic ) throws BoardException { if ( topics . containsKey ( topic ) ) { throw new TopicExistsException ( ) ; } topics . put ( topic , new LinkedHashSet < > ( ) ) ; }
addTopic to the Board.
addTopic to the Board .