public UserEntity createUser(String userName, String localUserName, String displayName) throws AmbariException {
    return createUser(userName, localUserName, displayName, true);
  }
Creates new, active, user with provided userName, local username, and display name.

@param userName      user name
@param localUserName the local username to use; if <code>null</code> or empty, userName will be used
@param displayName   the name to display for presentation; if <code>null</code> or empty, userName will be used
@return the new UserEntity
@throws AmbariException if user already exists
ambari-server/src/main/java/org/apache/ambari/server/security/authorization/Users.java