public EmployeeListViewModel(IMessageBroker messageBroker, IEmployeeService employeeService,
                                     NewEmployeeCommand newEmployeeCommand, EditEmployeeCommand editEmployeeCommand,
                                     DeleteEmployeeCommand deleteEmployeeCommand)
        {
            this.messageBroker = messageBroker;
            this.employeeService = employeeService;

            NewCommand = newEmployeeCommand;
            EditCommand = editEmployeeCommand;
            DeleteCommand = deleteEmployeeCommand;

            employees =new ObservableCollection<Employee>();

            NavigationCommands = new List<CommandBase>() {NewCommand, DeleteCommand};
            SubscribeMessages();
        }
        public EmployeeListViewModel(IMessageBroker messageBroker, IEmployeeService employeeService,
                                     NewEmployeeCommand newEmployeeCommand, EditEmployeeCommand editEmployeeCommand,
                                     DeleteEmployeeCommand deleteEmployeeCommand)
        {
            this.messageBroker   = messageBroker;
            this.employeeService = employeeService;

            NewCommand    = newEmployeeCommand;
            EditCommand   = editEmployeeCommand;
            DeleteCommand = deleteEmployeeCommand;

            employees = new ObservableCollection <Employee>();

            NavigationCommands = new List <CommandBase>()
            {
                NewCommand, DeleteCommand
            };
            SubscribeMessages();
        }