@Override
  public boolean equals(Object o) {
    if (this == o) {
      return true;
    }
    if (!(o instanceof User)) {
      return false;
    }
    return ugi.equals(((User) o).ugi);
  }
Returns true if user credentials are obtained from keytab.
hbase-common/src/main/java/org/apache/hadoop/hbase/security/User.java