private boolean isStringEquals(String s1, String s2) {
    if (StringUtils.isBlank(s1)) {
      return StringUtils.isBlank(s2);
    }
    return s1.equals(s2);
  }
For replication peer cluster key or endpoint class, null and empty string is same. So here
don't use {@link StringUtils#equals(CharSequence, CharSequence)} directly.
hbase-server/src/main/java/org/apache/hadoop/hbase/master/replication/ReplicationPeerManager.java