EmployeeDuty_noInv.cs

  var db = new SQLiteConnection(new SQLitePlatformAndroid(), Constants.DbFilePath);
  db.CreateTable<Employee>();
  db.CreateTable<Duty>();

  var employee = new Employee
  {
      Name = "Andrew",
      LastName = "Programmer"
  };

  var duty1 = new Duty()
  {
      Description = "Project A Management",
      Deadline = new DateTime(2017, 10, 31)
  };

  var duty2 = new Duty()
  {
      Description = "Reporting work time",
      Deadline = new DateTime(2022, 12, 31)
  };

  db.Insert(employee);
  db.Insert(duty1);
  db.Insert(duty2);

  employee.Duties = new List<Duty> {duty1, duty2};
  db.UpdateWithChildren(employee);

  var employeeStored = db.GetWithChildren<Employee>(employee.Id);