/**
  * Function to check whether a role is existing 
  *
  * @param string $roleName 
  * @return IsExistingRoleResponse
  */
 public function isExistingRole( $roleName) {
     $parameters = new IsExistingRole();
     $parameters->roleName = $roleName;
     $this->serviceStub->isExistingRole( $parameters)->return;
 }