public class Payment
{
    [Key]
    public int Payment_ID { get; set; }

    [Required]
    public decimal Amount { get; set; }

    [Required]
    public DateTime Payment_Date { get; set; }

    public int Contract_ID { get; set; }

    [ForeignKey(nameof(Contract_ID))]

    public Contract Contract { get; set; }



    public int Payment_Type_ID { get; set; }



    [ForeignKey(nameof(Payment_Type_ID))]

    public Payment_Type Payment_Type { get; set; }
}

//appDbContext
var Payments = new Payment[]
{
  new Payment { Payment_ID = 1, Amount = 50.00m, Payment_Date = new DateTime(2024, 4, 12), Contract_ID = 1, Payment_Type_ID = 1 }
};
builder.Entity<Payment>().HasData(Payments);