public UserSession::getDisplayName()
Returns the display name of this account.
By default, the passed-in object's 'name' property is used if it exists, or else, the site-defined value for the 'anonymous' variable. However, a module may override this by implementing hook_user_format_name_alter(&$name, $account).
Return value
string|\Drupal\Component\Render\MarkupInterface Either a string that will be auto-escaped on output or a MarkupInterface object that is already HTML escaped. Either is