public @Test final void testSetUsersNegative(){
  Role role=new Role(TEST_ROLE);
  thrown.expect(IllegalArgumentException.class);
  role.setUsers(null);
}

public @ Test final void testSetUsersNegative ( ) { Role role = new Role ( TEST_ROLE ) ; thrown . expect ( IllegalArgumentException . class ) ; role . setUsers ( null ) ; }
setting the list of grants to null is not allowed .
