System.Security.Permissions.PrincipalPermission.Intersect C# (CSharp) Method

        public IPermission Intersect(IPermission target)
        {
            if (target == null)
            {
                return null;
            }
            else if (!VerifyType(target))
            {
                throw new ArgumentException(SR.Argument_WrongType, GetType().FullName);
            }
            else if (IsUnrestricted())
            {
                return target.Copy();
            }

            PrincipalPermission operand = (PrincipalPermission)target;

            if (operand.IsUnrestricted())
            {
                return Copy();
            }

            List<IDRole> idroles = null;
            foreach (IDRole idRole in _idArray)
            {
                foreach (IDRole operandIdRole in operand._idArray)
                {
                    if (operandIdRole.Authenticated == idRole.Authenticated)
                    {
                        string newID = string.Empty;
                        string newRole = string.Empty;
                        bool newAuthenticated = operandIdRole.Authenticated;
                        bool addToNewIDRoles = false;

                        if (operandIdRole.ID == null || idRole.ID == null || idRole.ID.Equals(operandIdRole.ID))
                        {
                            newID = operandIdRole.ID == null ? idRole.ID : operandIdRole.ID;
                            addToNewIDRoles = true;
                        }
                        if (operandIdRole.Role == null || idRole.Role == null || idRole.Role.Equals(operandIdRole.Role))
                        {
                            newRole = operandIdRole.Role == null ? idRole.Role : operandIdRole.Role;
                            addToNewIDRoles = true;
                        }
                        if (addToNewIDRoles)
                        {
                            if (idroles == null)
                                idroles = new List<IDRole>();
                            idroles.Add(new IDRole(newAuthenticated, newID, newRole));
                        }
                    }
                }
            }

            return (idroles == null) ? null : new PrincipalPermission(idroles.ToArray());
        }

		public void IntersectWithBadPermission () 
		{
			PrincipalPermission p1 = new PrincipalPermission ("user", null);
			EnvironmentPermission ep2 = new EnvironmentPermission (PermissionState.Unrestricted);
			PrincipalPermission p3 = (PrincipalPermission) p1.Intersect (ep2);
		}