code: public TcpIpConfig addMember(String member) {
          String memberText = checkHasText(member, "member must contain text");
  
          StringTokenizer tokenizer = new StringTokenizer(memberText, ",");
          while (tokenizer.hasMoreTokens()) {
              String s = tokenizer.nextToken();
              this.members.add(s.trim());
          }
  
          return this;
      }
docs: Adds a 'well known' member.
  <p>
  Each HazelcastInstance will try to connect to at least one of the members, to find all other members,
  and create a cluster.
  <p>
  A member can be a comma separated string, e..g '10.11.12.1,10.11.12.2' which indicates multiple members
  are going to be added.
  
  @param member the member to add
  @return the updated configuration
  @throws IllegalArgumentException if member is {@code null} or empty
  @see #getMembers()